Elgin HT-HT Best Practice

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ELGIN /FRANKLINHP/HT BEST PRACTICES& GUIDELINESDRILLING FLUID /CEMENTINGREVISION 00

HP/HTBest Practices and Guidelines

ELGIN / FRANKLIN

Development

Volume 1

- DRILLING FLUIDS- CEMENTING- HYDRAULICS

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Central Graben Asset :

Subsurface Manager 1 Copy

Drilling & Completion Department :

DCD Library ( archives ) 2 CopiesDrilling & Completion Manager 1 CopyDrilling Superintendent 1 CopyDrilling Fluids Advisor 1 Copy

Elf Exploration Production :

EP/T/ER/CPU 1 Copy

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Foreword

The purpose of this document is to report the experience gathered during the drilling of the extremehigh-temperature / high pressure[HPHT] wells on ELGIN / FRANKLIN field with GALAXY 1 andMAGELLAN .This is done in order to make it available to the people in charge of such particular well , but also togenerate discussion on this up to date topic within drilling people with similar experience .

This report describes developments in the management of drilling fluids for use in High - Pressure ,High - Temperature wells .Section 1 to 8 of this present document concern the successful role of the Fluids ; Cementing andHydraulic in the drilling phase of this project . It’s presented close to a detailed programme with thethree main parts :

1. Programme / Execution -2. Achievement –3. Experience transfer ; rules of Thumb ; Recommendations .

A separated Fluids / Cementing / Environment report has been issued per well with a detailed report.

Selection of Drilling Fluid for HP/HT well :

The philosophy of the mud optimisation is to improve overall drilling efficiency so the well can beeconomically drilled . The aim is to design mud rheology and hydraulics in such way that minimumdrilling incidents and maximum drilling efficiency can be achieved . Mud selection and maintenanceare absolutely essential to the successful drilling of a hostile environment with BHP over 1200 barsand bottom hole temperature in excess of 200 °C .The deliberate choice of an invert emulsion presents obvious advantages for well integrity .The co-operation between EEUK ; ELF Exploration Production , mud Laboratory and the drilling fluidssupervision are essential to obtain the most from this drilling fluid .

The chosen XP07 mud system developed by Baroid should be capable of satisfying all of thefollowing critical issues :

• Minimal rheology through a low kinematic viscosity of the base oil .• Medium but not progressive thixotropy• Good suspending characteristics to avoid sagging of weighting materials .• High resistance & stability to contaminants under HP / HT conditions .• Efficient sealing of the porous and permeable formation with Over-pressure up to 88 bars in static

across the reservoir , and to 150 bars in front of the Palaeocene sandstone .• Good lubrication .

Selection of Cementing company for HP/HT well : The technical results showed that the two contractor’s Dowell and Halliburton , were competent withthe qualification exercise and ELF specifications for the HP/HT challenge .

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Due to the extreme conditions and the limit of the present technology in this range of temperature , itwas decided to keep the both major cementing contractor’s on the separate rig . The needs for optimisation , adjustment and correction of the current practices , innovation ,Engineering and improvements was the key factor of the decision . It was considered that by having two contractors the services would be kept at a high level with :• A long term competition• The involvement of two engineering instead one .• The gain of a valuable expertise .

This report contains information on how the entire cementing process was optimised for HPHT fielddevelopment . Improvement to the equipment , the slurry testing , the placement and bond loggingprocedures are presented .

Elf are developing a “ DMS which , among other things allows wells to be planned , drilled andperformances analysed so that “ lessons learned “ are carried forward into subsequent wells .This philosophy was applied to the drilling of these 11 HPHT wells with ELF and BAROID off andon shore personnel involved at the planning stage , drilling , monitoring and recording phase , andevaluation / analysis of performances . Programmes and pre-spud meetings provided the link fromplanning to drilling , the Final well Report and debriefing meetings from drilling to evaluation .Agreed recommendations carry “ the lessons learned “ into the planning of the next well . A “ HPHT“ Best practices “ Book is being developed for inclusion into the DMS and is designed to bridge anygap in the HPHT drilling schedule .

The pre-planning phase involved the ELF Drilling Team in ABERDEEN , ELF Research Centre inFRANCE and the Mud Company BAROID with field proven Synthetic Mud system .

September, 99

E E LF’sLF’s Drilling M anagem ent System Drilling M anagem ent System

D.M.S

PLAN DRILL MONITORRECORD

EVALUATION& ANALYSIS

Best Practices Lessons Learned

Pre-Spud MeetingPrograms

FWR & DebriefingMeeting

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Personnel. Team building and competency were key issues at the start on the project and minimisingpersonnel turnover as the project progressed was another.

Geology Mud CementSea bed 140m 36" Phase 30" casing

Mud Type Lead slurry 1.55SGNordaland Group S.W + Hi Vis Pills Neat cement 1.92SG

or XLITe 1.56SG26" Phase 20" casing:

G+SilicaMud Type: Lead slurry 1.44SGBentonite + Gel Neat cement 1.92SG

TOC surfaceMW: 1.10/1.19 SG

Hordaland Group 17½" Phase 13 3/8" casing:

Mud Type: G + 35% SilicaSBM:XP07 or ESTER Lead slurry 1.66SG

+/- 1600m Neat cement 1.92SGMW: 1.55/1.65 SG

Paleocene TOC surface

Balder +/- 3300mSale +/- 3350mLista +/- 3400mAndrew +/- 3480mEkofisk +/- 3680m

Tor +/- 3800m BHST: 145°cUpper Cretaceous 12¼" Phase 10 3/4" x 9 7/8"casing

Mud Type G + 35% SilicaHod +/- 4350m SBM: XP07

Lead slurry 1.66SGMW: 1.35 to 1.70 SG Neat cement 1.92SG

TOC +/- 200mabove Xo 9 7/8" x 10 3/4"

Herring +/- 5100m

Plennus Marl+/- 5280mHydra +/- 5290m

Lower Cretaceous BHST: 180°cRodby +/- 5390m 8½" Phase 7" LinerSola +/- 5440mValhall +/- 5500m Mud Type G + 35% SilicaKimmeridge Clay SBM: XP07Heather +/- 5560m MW: 2.15 to 2.17 SG Neat slurry: 2.30 SGFranklin sands

Pentland BHST: 180°c

MUD & CEMENTING

30" CP at 200m

Deviation 20 to 40°

Deviation 0 to 15°

Deviation 20 to 0°

Deviation +/- 0°

20" casing @ 900m

13 3/8" casing @ 3600m 72# p110

9 7/8" x 10 3/4" @ 5200m 66.9# Q125 - 110.2# C110

7" Liner @ 5900m 42.7# 125.25 Cr

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ELGIN / FRANKLINELGIN / FRANKLINELGIN / FRANKLINELGIN / FRANKLIN

HP/HT BEST PRACTICES & GUIDELINESHP/HT BEST PRACTICES & GUIDELINESHP/HT BEST PRACTICES & GUIDELINESHP/HT BEST PRACTICES & GUIDELINES

DRILLING FLUID ,CEMENTING & HYDRAULICDRILLING FLUID ,CEMENTING & HYDRAULICDRILLING FLUID ,CEMENTING & HYDRAULICDRILLING FLUID ,CEMENTING & HYDRAULIC

REVISION 00REVISION 00REVISION 00REVISION 00

1

ContentsVOLUME 1

1 36”(or 42” x 36”) SECTION

1.1 Purpose1.2 Drilling procedure1.3 Expected problems1.4 Drilling fluid1.5 Experience1.6 30" (or 30”x 36”) casing and cementing1.7 Experience

2 26” SECTION2.1 Purpose2.2 Expected problems2.3 Drilling fluid2.4 Experience2.5 20" casing and cementing2.6 Experience

3 17 ½” or 16” SECTION3.1 Purpose3.2 Expected problems3.3 Drilling fluid – Experience - Hydraulic3.4 Recommendations ( Table ) - Borehole Stability in the Hordaland3.5 14” x 13 3/8” casing and cementing3.6 Experience – Recommendations ( Table )3.7 Cementing recommendations

4. 12 ¼” SECTION4.1 Purpose4.2 Drilling procedure4.3 Expected problems4.4 Drilling fluids – Experience - Hydraulic4.5 Recommendations ( Table )4.6 10 ¾ “ x 9 7/8” (casing or Liner ) and cementing4.7 Experience

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4.8 Recommendations ( Table )4.9 Temperature simulation

5. 8 ½” SECTION – HP/HT5.1 Purpose5.2 Drilling procedure – Hydraulic Tests5.3 Expected problems5.4 Drilling fluids - Hydraulic5.5 Experience - Recommendations ( Table )5.6 7” ( or 7”x 4 1/2” ) liner and cementing5.7 Experience5.8 Recommendations ( Table )5.9 Temperature simulation – Enertech / Cemcade software

6. 5 5/8” SECTION .6.1 Purpose6.2 Drilling procedure6.3 Expected problems6.4 Drilling fluids6.5 Experience6.6 4 1/2” liner and cementing6.7 Experience – Recommendations ( Table )

7. MECHANISMS OF WELLBORE Instability in the TRANSITION ZONE7.1 Wellbore Instability7.2 How to recognise a well instability ?7.3 Reasons for well instability7.4 Guide lines – Experience7.5 Matrix7.6 Stragegy7.7 Fluid Simulator - ECDELF Software7.8 Field results – Conclusions7.9 Hydraulic Tables7.10 81/2” PWD Interpretation

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8. COMPLETION. - NON PERFORATED WELLS

8.1 Purpose8.2 Well Clean up Procedure8.3 Inflow test – Horner plot8.4 Well Control – Pipe light scenario with 1.00SG fluid

9. COMPLETION. - PERFORATED WELLS – CESIUM FORMATE BRINE

9.1 Purpose9.2 Well Clean up Procedure9.3 Inflow test9.10 Experience

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INDEX :

Additives , Cement : Section , pageAlkalinity : section ,page

Borehole stability : Section pageBatch mixing : section , pageBaracarb : section ,pageBHCT evaluation : section ,pageBHST evaluation : section , pageBarite plug : section ,pageBrine : section ,page

Cementing Practices : section ,pageCavings : Section ,pageCBL records : section , pageCompressive strength : section , pageContract : section ,pageCompressibility : section , pageCement class : section , pageCement plug : section , pageCEMCADE : section , pageCESIUM brine : section ,pageChanneling : section , pageChemical concentration : section ,pageCentralisers : section ,pageConsistometer : page , sectionCompatibility tests : section ,pageCoring : section ,pageCompressibility : section ,page

Displacement : section ,pageDensity : section , pageDye : section , pageDifferential sticking : section , page

ECD : section , pageESD : section , pageExcess of cement : section , pageEnertech : section , pageECDELF : section , pageESTER mud : section , pageEvaporation : section , page

Electic Stability [ES] : section ,pageEmulsifier : section , page

Flow rate : section , pageFlash point : section ,pageFann 70 : section ,pageFlow check procedure : section ,page

Gumbos : section , pageGels : section , page

Hydraulic : section , pageHigh vis pill : section , pageHole cleaning : section , pageHorner plot : section , pageHP/HT fluid loss : section ,pageHydrates : section , pageHordaland shales : section ,pageHigh pressure test : section ,pageHP/HT cementing plugs : section ,pageHydraulic Tests : section ,page [H2S : section ,pageHP/HT Drilling practices : section ,pageHP/HT Rheometer : section ,page

Inflow test : section pageID measurement : section ,pageIncentive : section ,page

Kill mud : section , pageKimmeridge clay : section ,page

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Lead Slurry : section , pageLight slurry : section , pageLosses : section , pageLOT : section , pageLogistic/Supply : section , pageLow vis pill : section , pageLCM selection : section , pageLiner cementing : section , page

Mud lab TestMud cooler : section , pageMud system : section , pageMud pits : section , pageModeling software : section ,page

Oil on cuttings : section , pageOil Water ratio : section ,pageOil based mud procedures : section ,page

Safety margin : section , pageSagging : section ,pageSacrificial mud : section , pageShoe track : section , pageSlurry volume : section ,pageSafety stock : section pageScreens : section , pageShakers : section , pageSolids control : section , pageSwab and Surge calculations : section ,pageSpecific Laboratory Tests : section ,pageSupercharging : section , page

Personnel : section , pagePressure Test : section pagePumps : section , pagePumping sequence : section ,pagePWD tool : section ,pagePollution : section ,pagePressure Transmission : section ,page

Quality : section , page

Rig capacity : section , pageRemedial cement job : section , pageRheology : section , pageRetarder sensibility : section , page Stinger : section ,page

: section , page: section , page: section , page

Tail Slurry : section ,pageTOP CEMENT : Section pageThickening time ; section , pageTop job : section , pageTemperature modelling : section , pageTransition zone : section , pageTiming : section , pageTripping Speed : section ,pageTemperature reference SG : section , page

: section , page: section pagesection , page

Wiper trip : section , pageWell Instability: section , pageWellsite procedures : section , pageWell clean up : section , pageWeighting agent : section ,page

Zinc Bromide : section ,page

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1 36”(or 42” x 36” ) SECTION :

Interval : +/- 140 to 230 mMax expected BHP : 1.09 E.M.W.

1.1 Purpose :Platform wells : Install the 30” casing and the retrievable guide base structure.Pre-drilled wells : Install the 36”x 30” casing with MLS.

1.2 Drilling procedure :Drill the 36" hole to approximately 235m using a stabilised string with a 26" bit and 36"hole opener. Sea water and high viscosity gel slugs will be used to clean the hole.At the TD displace hole with 1.15 SG mud.Wiper trip before pulling out of hole.For the pre-drilled wells, open hole 42” to 15m below the mud line in one pass with 36”assembly ( i.e. 42” hole opener incorporated in the 36” string).

1.3 Expected problem :Hole cleaning / large amount of cuttings.

1.4 Drilling fluid :Sea water with viscous mud slugs and return lost at seabed.Pump at least 2 slugs of 8 - 10 m3 of viscous mud every 10m drilled or as required for holecleaning. A 16 m³ viscous slug should be pumped around the casing depth, to sweep thehole.Before the check trip (if deemed necessary) and before running the casing, the hole shouldbe over-displaced by 50% of open hole volume with bentonite high viscosity mud. Thefinal displacement should be weighted to 1.15 SG to avoid any tight hole or excessive fill.During entire drilling phase, keep a kill mud reserve of 1.15 SG (one hole volume).

1.4.1 Typical composition of mud

Typical composition of viscous pills:

Sea waterGuar Gum 8 to 10 kg/m³

orFresh waterCaustic soda 1 to 2 kg/m³Soda Ash0.5 kg/m³Bentonite 80 to 100 kg/m³

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Typical composition of displacement mud:

Fresh waterSoda Ash 0.5 kg/m³Caustic soda 1 kg/m³Bentonite 80 - 100 kg/m³Barite 210 kg/m³CMC HVT 2 to 3 kg/m³

1.4.2 Typical mud characteristics

Weight : 1.05 / 1.15Funnel viscosity : > 100 sec.Required mud volume : 500 m³

1.4.3 Safety stocks

Bulk material:Barite : 150 t Bentonite : 50 t Cement G : 100 t

1.4.4 Minimum stocks of chemicals in sacks or drums required:

Caustic soda : 5 tLCM F/M/C : 3 t/ 3 t/ 3 tSodium bicarbonate : 1 tSoda ash : 2 tCMC HV/LV : 3 t/3 tPipe free : 2 m³Cement accelerator (CaCl2) : 3 t

1.5 EXPERIENCE

1.5.1 TYPE OF MUD USED.Types Used Recommended

Gel Spud mud / Guar gum / ViscousSweeps

Gel Spud mud / Guar gum / ViscousSweeps

1.5.2 DENSITY.

Density Used Density Recommended

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1.15 Kill / Spotting fluid 1.15 Kill / Spotting fluidUnweighted spotting fluid Unweighted spotting fluidUnweighted sweep fluid Unweighted sweep fluid

1.5.3 MUD BUILT.

Type & Weight Used RecommendedGuar gum at 1.03 SG. Guar gum at 1.03

Gel mud at 1.07 to 1.15 SG. Gel mud at 1.07 to 1.15 SG.Volume Built / Used Recommended

760 / 450 m3. 500.0 m3.

1.5.4. PIT MANAGEMENT.

Pit space on the Galaxy I or Magellan is generally not a problem because of the largecapacity that this new generation of rig .

Recommendations:

- RIG SELECTION : Need a large Mud pit capacity . ( 600 m³ minimum ) - High mixing rate for bulks to the pit is necessary . - The pits must be selected on the basis of the valves the derrickman needs

to operate for the frequent sweeps and the lines needed to spot highviscosity mud on bottom .

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1.6 30" ( or 30”x 36” ) casing and cementing Cementing job with STINGER : - Before cementing wash cuttings around wellhead. - Check free circulation with viscous sea water. - The 30" casing (or 36”x 30”) must be cemented up to seabed or Mud Line Suspension. - To estimate the hole volume, a sea water spacer with dye will be pumped ahead the

slurry, and the return will be monitored by ROV. - When the spacer is seen at the mud line ( Identification at the sea bed with R.O.V not easy ) ,the

open hole volume will be assessed and slurry volume will be adapted in order to fill the annulus(provide for 200% excess on theoretical volume).

Slurry volume calculations :

36” hole volume: 656.7 l/m E.A. 36”/30” volume : 200.6 l/m 5” DP inside volume: 9.05 l/m Annulus volume: 19 m³ Spacer volume: 20 m³ Tail slurry volume (200% of excess) 75 m³ Displacement (stinger) 2 m³

Fluids Design: - Spacer

Sea water + Dye - Lead slurry

G cement (Dyckerhoff or Lafarge ) 35% Silica 350 kg/t Sea water 1218 l/t D144 or NF5 Antifoam 1 l/t D020 Bentonite 15 kg/t Or D111 Thixotropic agent 70 l/t

- Tail slurry

G cement (Dyckerhoff or Lafarge ) 35% Silica 350 kg/t Drill water 550 l/t D144 or NF5 Antifoam 1 l/t CaCl2 20 kg/t Cement Slurry properties :

! Lead slurry

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Density 1.55 SG Yield 1740 l/t Thickening Time 6h00 - 8h00

! Tail slurry

Density SG 1.90Yield 1006 l/tThickening Time 4h00 - 5h00Compressive strength > 100 bar in 24 h

Consumption expected:

G + S Cmt + Silica 92 tAntifoam 80 lBentonite 250 kgCaCl2 1150 kgThixotropic agent 1100 l

When cement operation has been successfully verified by ROV, stop pumping slurry anddisplace with sea water until top of cement inside 30" casing is approx. 5 m above the shoe.Depending on the quality of the primary cementing job, a cement top job may have to beperformed.In case of MLS system, displace sea water + retarder to wash the MLS equipment.

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1.7 EXPERIENCE :

Surface and conductor casings provide the foundations for the construction of an oil /gaswell Cement plays a major role in re-enforcing the casing in the formations near the surfacethat are weak and non-consolidated .To address and minimise these problems a new Cementblend has been developed giving a high strength at a low temperature ( +/- 10 °C ) with anominal weight of 1.45 / 1.56 SG .This slurry is Thixotropic with a gelling period of less than an hour ( in static conditions ) .

Recommendation :

- The X-Lite blend can eliminate remedial jobs , reduce W.O.C time .

- Use Class G cement without any Silica , no impact on the casing design( thermal degradation in production phase )

- Identification of Dye with sea water at sea bed with R.O.V is very challenging .

- Volume to be pumped as a minimum is : 80 m³ .

CEMENTING PROCEDURE Applied on F3 & 29/4D-4 :

Ref : { HALLIBURTON Design X-Lite Blend }

- Running Procedure and centralisation : ( see UWG detailed procedure ).Note : The casing will be filled up with sea water .

Pumping Sequence :

1 - 25 m³ of Sea water +Sapps to break gels

2 - Spacer 500 E+ : 15 m³ ( see Hallibuton formulation ) SG = 1.30

3 - 3 / 5 m³ of Sea water + fluorescene

4 - Mix and pump 75 m³ of X-Lite slurry : SG =1.52 @ surface - 1.56 SG @ bottom

One Annular volume +/- 26 m³ ( theoretical )Slurry yield = 1033 l/ton of X-Lite blended

Cement X-Lite 1 ton 72 tons( blended )Sea Water 753 l/ton 39 m³Defoamer 1 l/ton 50 litersCaCL2 40 kgs/m³ of SW 1560 kgs

Thickening Time : 5 hours

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Compressive Strength : 1476 PSI @ 10°C 24 hours.

NOTE :

It is recommended that extra mix water is prepared for X-Lite slurry and that the slurry ismixed and pumped until all the X-Lite Blend has been used .Contingency Tail Slurry design . If after pumping all the X-Lite slurry there are still noreturns at sea bed , the X-Lite mix water can be used to prepare a 1.90 SG slurry mixed withLafarge G+S .See formulation attached .

X-Lite slurry is THIXOTROPIC with a Gelling period of less than an hour ( STATICconditions ) Thus any prolonged shutdowns must be avoided .

5 - Displacement with sea water at 2000 l/min .

Monitor continually the return with ROV .If there is no sign of cement return , the volumewill be limited to 4 times the theoretical annulus volume . A complementary cementationwill be made after cement has set .( a formulation with G+S will be used as tail slurry ) iflosses/problems whilst drilling 26” section .Check for back flow . If there is some return , check volume and pump same volume .Waitfor cement samples .Differential pressure = + 2 bars ( positive )

6 - Timing :

Mixing + Pumping Slurries = 100 minDisplacement N° 1 = 3 minSafety factor = 60 minTotal = 163 min

7 - Excess volume versus hole volume :

Estimated Diameter Annul. Volumehole/casing Slurry Volume

Volume Planned Excess in%

40 “ 350 l/m 36 m³ 75 m³ 110 %42 “ 432 l/m 44 m³ 75 m³ 70 %44 “ 518 l/m 53 m³ 75 m³ 41 %46 “ 608 l/m 62 m³ 75 m³ 20 %

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8 – Well Recap :

WellsLead Pumped Tail Pumped Total Remarks Top Job

22/30 – C G4 20 m³ @ 1.55 SG 66 m³ @ 1.92 SG 86 m³ Observe return after 59m³ pumped No

22/30 – C G5 27 m³ @ 1.55 SG 70 m³ @ 1.92 SG 97 m³ No return of spacerobserved

No

22/30 – C G6 21 m³ @ 1.55 SG 73 m³ @ 1.92 SG 94 m³ Return seen after 65 m³pumped

Unable to pumpthrough the line

22/30 – C G7 21 m³ @ 1.55 SG 73 m³ @ 1.92 SG 94 m³ Use G neat – Returnseen at the sea bed

Not able to pumpthrough the line

22/30 – C G8 21 m³ @ 1.55 SG 75 m³ @ 1.92 SG 96 m³ Use G neat – No returnclarified identified

Pump 13 m³ top job

29/5 B – F1 22.5 m³@1.55 SG 48.5 m³@ 1.92 SG 71 m³Good return at the seabed

Pumped throughthe line 29 m³ 1.90SG

29/5 B – F2 22m³ @ 1.55 SG 70 m³ @ 1.92 SG 92 m³ No return clrealyidentified

Pumped 27 m³ oftail slurry .

29/5 B – F3 X-Lite78 m³ @ 1.52 SG

Followed by 11 m³of Tail slurry

89 m³ Top cement inside 30”CP found 20 m above

shoe

Pumped 25 m³ oftail slurry

29/5 B – F4 X-Lite84 m³ @ 1.52 SG

Followed by 17 m³of Tail slurry

101 m³ ROV failure – Unable tocheck return

No

29/5 B – F5 21 m³ @ 1.55 SG 70 m³ @ 1.92 SG 91 m³

29/5 B – F6 X-Lite92 m³ @ 1.52 SG

17 m³ @ 1.90 SG 109 m³ Unable to see return

Well 29/5b-F3Date

Top of cement m 140 140Casing shoe m 229 230Height m 89 89 89 90 90 90BHST ºC 10 10BHCT ºC 10 10Type of slurry lead tail lead tail lead tail lead tail lead tail lead tailTheoritical slurry volume m³ 22.4 22.4 22.4 22.4 22.4 22.4 22.4 none 22.4 none 22.4 noneExcess %Total slurry volume m³ 22.4 48.3 22.4 48.3 22 70 78 11 97 20 92 17Weight of cement (G+S) ton 17 65 17 90 80 20 80 20 89 17Slurry weight sg 1.55 1.92 1.55 1.92 1.55 1.92 1.52 1.92 1.52 1.92 1.52 1.92

Cement Lafarge G Lafarge G Lafarge G Lafarge G Lafarge G Lafarge G X-Lite Lafarge G X-Lite Lafarge G X-Lite 100Silica flour % 35 35 35 35 35 35 35 35 35Water type 1/3fresh 2/3sea Sea 1/3fresh 2/3sea Sea 1/3fresh 2/3sea Sea Sea Sea Sea Sea Sea SeaAdditives 2.5% Bento 2.5% Bento 2.5% Bento

3% CaCl2 2% CaCl2 3% CaCl2 2% CaCl2 3% CaCl2 2% CaCl2 3% CaCl2 3% CaCl2 3% CaCl2 3% CaCl2 3% CaCl2 3% CaCl2

l/tonor%

Thickening time (70BC) hr:min 18:38 06:50 18:38 06:50 18:38 06:50 05:03 03:28 05:10 02:44 05:08 03:25Compressive strenght 12 hr PSI 830 520 420 350 500 300Compressive strenght 24 hr PSI 50 695 50 700 50 695 1500 900 930 670 1100 700Flow pattern laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminarSpacer type Sea water/mica/fluo Sea water/mica/fluo Spacer 500E+

sg 1.03 1.30Plug typeRemedial jobs type

1.03Stinger

1 top job

140229

1010

Sea water + dye1.03

140229

1010

StingerStinger Stinger Stinger

10

Spacer 500E+1.30

1 remedial + 1 top job 2 remedial + 1 top job None None

04/01/1999140230

10

01/02/1998 16/02/1998 19/02/1998 28/09/1998

29/5b FRANKLIN - 36" OPEN HOLE / 30" CASING CEMENTATION

29/5b-F1 29/5b-F5 29/5b-F2 29/5b-F4

220 220 300 300

107

140230

1010

400420

29/5b-F615/10/1999

None

Spacer 500E+1.32

Stinger

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2 26” SECTION

Interval : 230 to approx. 900 m TVDPressure gradient : hydrostatic (EMW)Expected temperature : 36°C BHST at 900m TVD

2.1 Purpose :To set the 20" casing at +/- 900m TVD BRT, above the under compacted clays and deepenough to cover all the unconsolidated sands.LOT : 1.80 SG EMW expected - 1.55 SG EMW required.

2.2 Expected problems :Severe losses in the sands @ +/- 280 m .Large mud capacity is required .Hole cleaning.Running 20” casing

2.3 Drilling fluid:This section can be drilled using a simple GEL/CMC drilling fluid. Down to a depth of600 m where mud making clays are encountered a bentonitic/CMC system will be used.Thereafter below 600 m bentonite additions will cease and dilution pre mixes of sea-water/CMC will be sufficient to control system properties.

2.3.1 Typical composition of mud:

Above 600 mSea waterCaustic soda 2 - 3 kg/m³Soda Ash as requiredPrehydrated Bentonite 30 - 50 kg/m³CMC LV 3 - 4 kg/m³CMC HV 2 - 3 kg/m³Barite as needed

Below 600 mSea waterCaustic soda 2 - 3 kg/m³Soda Ash as requiredCMC LV 4 - 5 kg/m³CMC HV 2 - 3 kg/m³Barite as needed

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Above 600 mWeight : < 1.13Funnel viscosity : 45 - 50PV : 15 - 20YP : 20 - 25Gels 0/10 : 6 - 10 / 10 - 25Filtrate API : 15 down to 8 ccpH : 9.5

Below 600 m

Weight : < 1.13Funnel viscosity : 45 - 50PV : 20YP : 20Gels 0/10 : 6 / 20Filtrate API : 8 ccpH : 9.5

Required mud volume :2000 m³

2.3.3 Safety stocks

Bulk material

Barite : 150 tBentonite : 50 tCement G + Silica Flour : 100 t

Material in sacks or drums

Caustic soda : 5 tLCM F/M/C : 3 t/ 3 t / 3 tSodium bicarbonate : 1 tSoda ash : 2 tCMC HV/LV : 3 t/ 4 tFree pipe : 2 m³CaCl2 : 3 t

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2.3.4 Maintenance Recommendations

- A significant dump and replace regime will be need to be employed to ensure controlof mud rheology and density. It is critical that the mud density is controlled below 1.13SG while drilling to avoid losses under dynamic conditions.

- While drilling ahead, sweep the hole with 10 m³ of bentonite slurry prior to eachconnection to ensure hole is kept clean. These sweeps can be incorporated into theactive system to assist in “mudding up”. Once mud making clays are encountered thesepills can be replaced by CMC Hi Vis to allow easier control MBT levels in the mudsystem.

- Density should be controlled under 1.13 SG while drilling. Increase to 1.15 SG priorPOOH to run casing.

- Flow rates must not be reduced unless it is not possible to keep up with hole mudlosses. Pump output is recommended to be > 4000 l/min.

- Instantaneous penetration rates should be controlled less than 90 m/h. Averagepenetration rates should only be reduced if the pump rate is lowered.

- Fluid loss should be maintained initially at less than 15 cc, reducing to 8 cc below600m to control swelling of the reactive shale. Increased additions of CMC in thepremix should control it.

- Hi-Vis sweeps should be used while drilling. It is recommended that a 10 m³ sweepshould be pumped such that is CLEAR of the BHA on the connections or as required.These sweeps can be formulated with bentonite above 600 m then using CMC Hi-Vis.

- In case of downhole losses under 5 m³/h add LCM to the system. If the losses increaseover 5 m³/h pump a pill of LCM as follow:

Mud from the systemCMC Hi-Vis for VM>150LCM F : 50 kg/m³LCM M : 50 kg/m³LCM C : 50 kg/m³

- NUT PLUG F , BAROFIBER “M” , MICA “M” ARE THE PRIMARY LCM

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2.4 Experience :

2.4.1 Type of mud used :

Type Used RecommendedSeawater and sweeps Not recommended

Bentonite/polymer Bentonite/polymer

Volume Built / Used Recommended@ +/- 2300 m³ m3 as required

2.4.2 Density

Density Used Density Recommended1.15-1.18 < 1.18 SG

2.4.3 Kill mud used.

Type & Weight Used RecommendedNone None

2.4.4 Desilter

To minimise the sand content and assist in controlling the mud weight use the mudcleaner as a desilter, i.e. dump cone discharge. Have a suitable number of spares on therig. Service the mud cleaner prior to starting the phase.

2.4.5. Shaker Screens

The gumbo shakers ( scalpers ) were dressed with 20 over 40 mesh screens. As soon asscreens became available the shakers were changed to 10 over 20 mesh screens so that theshakers could handle the volume.The THULE shakers were redressed with the last of the coarse shaker screens in stock onthe rig. The configuration of the bottom deck of the shakers was:

Top Section :

Shaker #1 84 x 84 x 105 x 105Shaker #2 52 x 84 x 105 x 105Shaker #3 52 x 84 x 105 x 105Shaker #4 52 x 105 x 105 x 105

Around 600 metres:

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Shaker #1: 105 x 105 x 105 x 105Shaker #2: 84 x 84 x 105 x 105Shaker #3: 84 x 84 x 105 x 105Shaker #4: 84 x 84 x 105 x 105Increase the number and selection of shaker screens kept in the store on the rig.

2.4.6. Pit management.No problems were encountered.

2.4.7. Personnel

During top hole drilling it is helpful to have extra roustabouts to help man the shakerhouse.

2.4.8 Drill WaterHave the maximum amount of drill water on hand for pre-hydration of bentonite whendrilling top hole.

2.4.9 Pump rateDo not exceed 4,200 litres per minute with the pumps. The surface equipment cannotprocess the mud at the higher pump rates. Too much drilling fluid is lost from the shakersat the higher pump rates.

Recommendations:

- GUMBOS OBSERVED AT THE SHAKERS : ADDITION OF SEA WATER IS REQUIRED .

Losses :

- PARTIAL TO TOTAL LOSSES @ 280 M : SPOT HI VIS PILL FOLLOWED BY A LCM PILL AT ACONCENTRATION OF 150 KGS/M³ ( 15 / 20 M³ ) .

- SET CEMENT PLUG TO CURE LOSSES WITH CACL2 IF NO SUCCESS WITH LCM .SPOT LCMPILL ( 150 KGS/M³ ) AHEAD A HI-VIS PILL FOLLOWED BY A SLURRY WITH 2% OF CACL2 -

- RUNNING 20” CASING AT TD :

PUMPED 15 M³ OF PILL ( CAUSTIC / DETERGENT ) FOLLOWED BY 30 / 40 M³ OF MUD +70/80 KGS/M³ OF NUT COARSE @ 1.19 SG

– DISPLACE WELL WITH 90 M³ HI-VIS MUD @ 1.19 SG -

- PIT VOLUME : RIG SELECTION , ENSURE THAT THE MINIMUM CAPACITY IS 600 M³ .

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2.5 20" casing and cementing (shoe at approx. 900 m TVD) Cementing job with long STINGER : - Due to the high porosity / high permeability of the sands drilled and the risks of losses

the 20" casing will be cemented with two slurries:• Tail slurry 1.90 SG from the 20” shoe to +/- 700 m• Lead slurry to the seabed or MLS - To estimate the hole volume, a sea water spacer with dye / LCM will be pumped ahead

the lead slurry, and the return will be monitored by ROV. - When the spacer is seen at the mud line, the open hole volume will be assessed and the

slurry volume will be adapted accordingly in order to fill the annulus. Slurry volume calculations

26” hole volume: 342.5 l/m E.A. 26”/20” volume : 139.4 l/m 5” DP inside volume: 9.05 l/m Spacer volume: 20 m³ Lead slurry volume (100% of excess) 175 m³ Tail slurry volume (50% of excess) 50 m³ Displacement (stinger) +/- 10 m³

Fluids Design: - Spacer

Sea water + Dye XCD Polymer 10 to 15 kg/m³ Barite For 1.25 SG

- Lead slurry

G cement (Dyckerhoff or Lafarge ) 35% Silica 350 kg/t Drill water / Sea water 1681 l/t Antifoam 1 l/t D075 or Bentonite Extender 35.5 kg/t or 2% BWOC

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- Tail slurry

G cement ( Dyckerhoff or Lafarge ) 35% Silica 350 kg/t Drill water 546 l/t Antifoam 1 l/t D060 or Halad 344 FLC 10 kg/t or 0.35% BWOC

Cement Slurry properties :

- Lead slurry

Density 1.44 SG Yield 2161 l/t Thickening Time 6h00 - 7h00

- Tail slurry

Density 1.92 SG Yield 999 l/t Thickening Time 5h00 Compressive strength > 150 bar in 24 h

When cement operation has been verified as successful by ROV or return identified atthe wellhead , stop pumping slurry and displace with sea water until top of cement insidethe 20" casing is approx. 7 m above the float. Bleed off pressure and check for back-flow before unlatching running tool and pullingout of hole. In the case of MLS, flush the 30”x 20”annulus above the MLS by pumping sea water ora solution of sugar through the ports. During this job the flushing pressure should notexceed pumping pressure at the end of displacement. A remedial cement job will be considered if the slurry is not back to the mud line orsurface.

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2.6EXPERIENCE : ( see Example below )

20” CEMENTING Procedure : Running Procedure and centralisation : ( see UWG detailed procedure + centralizerplacement). Note : The casing will be filled up with mud 1.15 / 1.16 SG . Stinger will be run to +/- 10 m above float collar + Vetco circulating head will be used forcement job . ( Stinger seal assembly is only available as a back up ).

- Circulation at bottom to reduce mud rheology –

Pumping Sequence :

1 - Spacer to break gels - 14 m³ with QBII or DESCO

2 - Spacer to be used : +/- 48 m³ of Spacer 500 - ( equivalent of tail slurry volume )Composition : Fresh water + Viscosifier ( 32 kg/m³ ) + Barite -SG = 1.30

Reminder : On F4 - Good interface between thin spacer and viscosified spacer , but poorinterface between spacer and lead slurry .( 20 m³ contaminated )

3 - Mix and pump Lead slurry : SG =1.45

Total volume +/- 180 m³ ( with Excess ) Slurry yield = 2126 l/ton

Cement G ( Lafarge ) + 35 % Silica 1 ton 114 tons( blended )Water (sea water)+50% Drill water 1660 l/ton 140 m³ ( 3 mud pits )DefoamerNF5 L 1 l/ton 80 litresBentonite 3% 2400 kgsCaCl 2 2% 1600 kgs

Thickening time = 12 h 30 min +Compressive Strength 10 bar in 24 hours

4 - Mix and pump Tail slurry : SG =1.92

Volume = 48 m³ Slurry yield = 982 l/ton

Cement G ( Lafarge) + 35 % Silica 1 ton 65 tonsFresh water 532 l/ton 25.5 m³ ( 160 bbls )Defoamer 1 l/ton 50 litersHalad 344 0.35 % 168 kgsThickening time = 5 h at 100 BCCompressive Strength 87 bar in 12 hours

154 bar in 24 hours @ 30°C

5 - Displacement with mud SG =1.15 at 1500 l/min-

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Monitor continually the return at flow line in case of channeling ( Ref. On G5 & F4 ).Check for back flow . If there is some return , check volume and pump same volume .Wait forcement samples .Final static pressure should be 45 bars at the end of displacement.

6 - Timing :

Mixing + Pumping Slurries = 235 minDisplacement N° 1 = 10 minSafety factor = 60 minTotal = 305 min

7 - Excess volume versus hole volume :

Theoritical Annulus volume + Overlap ( 30” X 20 “ ) + Shoe = 140 m³ -

DiameterAnnul. Volume

hole/casingEquivalentSlurry Volume

Volume Planned Equivalent Excess in% - Open Hole

26 “ 142 l/m 140 m³ 228 m³ 89 %28 “ 192 l/m 173 m³ 228 m³ 42 %29 “ 220 l/m 192 m³ 228 m³ 25 %30 “ 250 l/m 213 m³ 228 m³ 10 %

The first number is for an O.H diameter of 26” and the last one for 30” . Anything outside theselimits should be considered as suspect , like channeling , losses , …

Reminder : On “F4 “ a contaminated return has been reported after pumping a volume of 169m³ of Lead + Tail

Note : It has been very difficult to check the losses on F4 cement Job . Could you informeveryone ( mud loggers , Derrick-man & Mud Engineers ) that this issue is critical as the 20”casing is our foundation to handle all the weights as the 30” CP cement job is not reliable .

Recommendations :

- No wiper trip , Back reaming systematically before running casing

- The use blend cement is required (“ G + 35% of silica “ )

- Pump a pill to break the gel before the cement job .( SAPP )

- Use Stinger with stab-in device in case of surface leak .( stab in shoe )

- Well volume : gauge hole +/- 20 %

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RECAP :

Well Lead Tail Total Comments29/5 - B F1 134 m³ 48 m³ 182 m³ Water bushing was leaking29/5 - B F2 120 m³ 49 m³ 169 m³ Spacer back to surface29/5 - B F3 135 m³ 48 m³ 175 m³ Return cement29/5 - B F4 103 m³ 45 m³ 148 m³ Return cement29/5 - B F5 133 m³ 52 m³ 185 m³ Return cement ( access deck )29/5 – B F622/30 - C G4 175 m³ 54 m³ 229 m³ No cemt in the shoe track , Pb with plug22/30 - C G5 175 m³ 48 m³ 223 m³22/30 - C G6 128 m³ 48 m³ 176 m³ Spacer w/Breaker , Good return @1.40 sg22/30 - C G7 118 m³ 46 m³ 164 m³ idem22/30 - C G8 119 m³ 48 m³ 167 m³ Lead return @ 1.43 SG

Well 29/5b-F3Date

Top of cement mCasing shoe m 905 907 905 909Height m 670 205 672 205 670 205 670 199 670 209 670 211BHST ºC 36 36 36 36BHCT ºC 20 20 18 18Type of slurry lead tail lead tail lead tail lead tail lead tail lead tailTheoritical slurry volume m³ 83 35 83 35 83 35 83 35 83 35 83 35Excess % 60 50 60 50 76 60 70 42 30 42 30 30Total slurry volume m³ 120 49 120 49 133 52 135 48 103 48 102 40Weight of cement (G+S) ton 74 66 74 66 82.1 71.5 92 65 65 62 60 60Slurry weight sg 1.44 1.92 1.45 1.92 1.45 1.92 1.45 1.92 1.45 1.92 1.45 1.92

Cement Lafarge G % 100 100 100 100 100 100 100 100 100 100 1 1Silica flour % 35 35 35 35 35 35 35 35 35 35 35 35Water type ½fresh ½sea Sea ½fresh ½sea Sea ½fresh ½sea Sea ½fresh ½sea Fresh ½fresh ½sea Fresh ½fresh ½sea FreshAdditives 3% Bento 3% Bento 3% Bento 3% Bento 3% Bento 3% Bento

2% CaCl2 2% CaCl2 2% CaCl2 2% CaCl2 2% CaCl2 2% CaCl2

l/ton 1 lit NF5 1 lit NF5or 0.35%Hal-344 0.35%Hal-344 0.35%Hal-344 0.35%Hal-344 0.35%Hal-344 0.3% Hal-344%

Thickening time (70BC) hr:min 13:19 08:30 13:20 09:20 13:20 09:00 12:11 04:51 15:12 05:32 15:50 06:30Compressive strenght 12 hr PSI 1300 1100 670Compressive strenght 24 hr PSI 70 2100 280 2200 280 2200 130 2200 90 1650 90 1900Flow pattern laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminarSpacer type Spacer 500E+ Spacer 500E+ Spacer 500E+

sg 1.25 1.28 1.30 1.25Plug typeDisplacement type Sea water

StingerSea water

Stinger StingerSea water Sea water Sea water

Stinger1.25

Spacer 500E+ Spacer 500E+

Stinger

20

899

36

Surface

29/5b-F622/10/199912/02/1998 01/03/1998 09/03/1998 04/10/1998 11/01/1999

Surface Surface Surface Surface

29/5b FRANKLIN - 26" OPEN HOLE / 20" CASING CEMENTATION

29/5b-F1 29/5b-F2 29/5b-F5 29/5b-F4

StingerSea water

Surface

3618

Spacer 500E+1.25

911

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3. 17"1/2 or 16” SECTION

Interval : From 900 to +/- 4000 m( MD ) +/- 3600 m (TVD)Max expected BHP : 1.47 EMW (Hordaland)LOT at 20" shoe : 1.85 EMW required (for 15 m³ limited kick)Expected temperature : 135°C BHST at 3600m TVD

If the LOT is under 1.85 EMW at the 20” shoe, a remedial cement job will be performed.

3.1 Purpose:Set the 13 3/8” casing below the Palaeocene just into the Tor formation to cover over-pressured Hordaland Shales and the potentially weak Palaeocene sand.

3.2 Expected problems- Hole stability in the Nordland and Hordaland clays which are water sensitive , dispersive

and potentially over-pressured.- Danger of differential sticking in Palaeocene sandstone , and seepages losses .- Hole cleaning in deviated wells.

3.3 Drilling fluid – Experience – HydraulicThis hole section will be drilled using a synthetic oil base mud with mud weight 1.55SG.

3.3.1 Typical composition of mud ( 1.55 SG , 65/35 , 160 000 ppm WPS)

XP-07 (Base Fluid) 447 l/m³EZ MUL 2F (Primary Emulsifier) 32 - 45 l/m³Lime (Ca(OH)2) 11.5 kg/m³DURATONE HT (Fluid Loss Control) 12 - 19 kg/m³Water 246 l/m³GELTONE (Viscosifier/Gelling Agent) 5 kg/m³Calcium Chloride (CaCl2) 110 kg/m³Barite (Weighting Agent) 633 kg/m³RM 63 (Rheology Modifier) 1.5 - 2 l/m³

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Weight : 1.55 – 1.60PV : ALAPYP : 20 - 25 lbs/100ft³YS : 8 - 10 lbs/100ft³Gels 0/10 : 15/25 - 20/30Filtrate API : 0 ccFiltrate HP/HT : 3 - 4 ccE. S. : > 400 VCl-(Water Phase Salinity) : 160 g/lH/E : 65/35 - 70 /30Excess of Lime : 10 g/l

3.3.3 Safety stocks

Bulk materialBarite : 150 tCement G + Silica Flour : 100 t

Material in sacks or drumsBARACARB 50/150 : 3 t/ 3 tUltra seal : 3 tChemicals to mix 300 m3 of synthetic base mud

Kill mud / Synthetic Base Oil

Kill mud 1.75 SG : 50 m³Base Oil : 150 m³

3.3.4 Recommendations

Displacement to SBM: SBM/Base fluid should not be brought on board until platform wide containmentmeasures have been fully discussed with all rig crews and implemented. No base fluid spacer should be pumped between the sea water and the XP-07 mud. Itsinclusion will only add to the volume of contaminated interface. A small degree of contamination will take place. Divert the interface to a reserve pit onits return to surface. Condition the volume for later use in the 17 ½ “section. The first 10 m³ of XP-07 mud should contain one drum of oil wetting agent. The XP-07 mud system will be cold during displacement operation (YP>35 lbs/100ft²).The rheology will be reduced as the temperature of the circulating system increases.

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Dress the shale shakers (screens) accordinglyto avoid whole mud losses at the shale shakers. Until the XP-07 has been sheared through the bit and it’s temperature has increased,utilise coarse screens ( + 84 mesh) on the shale shakers to avoid unnecessary surfacelosses. Note that if the mud is a reconditioned stock then it will take less time to fullyyield. If the mud is predominantly new mud then it will take longer to fully shear up andyield. As the mud heats up and becomes less viscous, the screens should be progressivelychanged to a finest mesh which can cope with the flow rate in use. Displace the sea water from the well with the maximum available pump rates, reducingthe pump rates when the synthetic mud is close to the surface. A minimum of 600 m³ of fully-formulated XP-07 whole mud weighing 1.55 SG will berequired to displace the hole and enable drilling to proceed without the need to mix newvolume. An additional + 300 m³ of mud will be required during this section. By havingsufficient reserve volume of premixed mud available, the mud engineer and rig crew willbe free to concentrate on the maintenance of the active system while penetration rates arehigh. Reserves of XP-07 Base Fluid + 150m³, should be kept onboard for dilution, oil-water ratio adjustments and weight reductions. An estimate 950 m³ of XP-07 mud will be required to drill the section. 600 m³ will beshipped from town, with the balance being made offshore.

- Mud weight: A review of offset wells in the area indicates mud weight up to 1.74 SGhave been required to stabilise the Lower Tertiary. Some wells have experienced lossesduring running and cementing of 14”x 13 3/8” casing with mud densities above 1.60 SG. Formation pressure in this section are anticipated as being overpressured with the porepressure increases from 1.08 - 1.44 SG. Experience has shown that if these shale arepermitted to slough due to insufficient mud weight at the outset, rig time is likely to thelost whilst attempting to stop this occurrence by increasing mud density after the fact. An initial drill out weight of 1.55 SG is anticipated to be adequate for this interval.Further increases in the mud weight may be required to insure a stable wellbore and anyindications of hole instability e.g. caving, should be addressed immediately by reviewingthe mud density. This is especially true as the hole will be deviated to 25 degrees.

- Possible shale shakers screen blinding due to the size/shape of Palaeocene sand grains,hence the shale shakers should be attended to all times and screens size type/shape(oblong/square), and angle changed as required to prevent surface losses. Ensure basefluid wash guns are set up and operational at the shakers.

- Mud rheology: The XP-07 mud system has a good relatively flat rheological profile.This result in reduced ECD and permits greater circulating rates for given pump pressure.

It is recommended to maximise hole (and riser) cleaning: • Use the highest possible pump output / annular velocities.

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• Keep the Yield Point at 50°C between 20 and 30 lbs/100ft² with the Plastic Viscosity

as low as possible. • Optimise the low shear rheology using RM 63 and GELTONE II to suppress the

formation of cuttings beds, and assist in hole cleaning by maintaining the Yield Stressbetween 12 and 15.

• Maintain high initial gel strength giving rapid suspension of cuttings when the pumps

are off during surveys, or trips. This should be combined with flat gel strengthdevelopment.

• Use mechanical means (e.g. wiper trips, pipe rotation, reciprocation, back reaming

with the top drive, etc.) and weighted pills pumped prior to trips to assist with holecleaning.

• If a more viscous mud is required, suggest initial treatment to raise Yield Point to 28 -

30 and initial to + 15. • If further viscosity increases are deemed necessary to improve the muds carrying

capacity, increase the Yield Point and 6 RPM reading in increments of 5 lb/100ft². Anupper limit of 30 should be considered the upper limit to ensure optimisation ofhydraulics.

- Pumping rates: Bottom hole assemblies must be optimised such that pressure limitationsallow for pump rates of over 4,300 l/min. In addition, bit (e.g. PDC), MWD anddownhole motors (if used) should have a maximum possible I.D.’s and must be rated foruse with pump rates of this magnitude. The use of 6 5/8” and/or 5 ½ “ drill pipe isrecommended to enable 4,300 l/min to be achieved.Note particularly that pumps should be started slowly on running into the hole to avoidexcessive surge pressures on the formation which could cause pressure fluctuations anddestabilise the hole.

- Penetration rates: Penetration rate must be controlled to minimise the accumulation ofcuttings beds and prevent overloading in the annulus which would be detrimental to holecleaning and would exacerbate hole pack-off as well as loss of return /induced fracturing.Additionally, bit balling, as related to solids crowding in the mud, is also affected bydrilling rates. Very high instantaneous ROP will cause bit balling , hence the ROP mustbe controlled not only on an average basis but also over short drilling periods.

- Hole cleaning: To ensure that good hole cleaning is achieved in this section, it isrecommended that the Yield Point and Yield Stress be maintained as programmed. Pumprate should also be as recommended.Hole cleaning is a function of mud rheology, circulation rates and ROP. Any indication offailure to clean the hole adequately should be countered by increasing the circulation timeon connections and before trips. Maximum allowable pump rates must be used whencirculating the hole clean, do not circulate at less than drilling rates.

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Even with mud properties and flow rates optimised a hole cleaning problem may stilloccur. At the first indication of possible problems, pump a high viscosity/weighted pill(pump these pills prior the trips). This should be sized to cover 100 m of annular hole. Itis recommended that a 2.0 SG weighted pill be pumped around while rotating the string >150 rpm if possible.In the case of all pills do not stop or reduce the circulation rate before the pill(s) havebeen evacuated from hole. To do so will result in material dropping out of the pill andpossibly avalanching downhole.All attempts should be made to isolate weighted pills on surface for re-use.Return of all pills should be monitored at the shakers, to gauge their effectiveness.

The trend in the correlation of cuttings generated and seen at the surface to ROP canprovide another indication of the effectiveness of hole cleaning. The mud engineersshould be monitoring cuttings volumes and correlating with these drilling rates at alltimes. The shaker hands should also be shown what to watch for so that they can providea speedy warning e.g. a soft sticky must means the cuttings are being reground in the welland are not being removed.

- Seepage losses/differential sticking: Since mud weight increases above normal will berequired to stabilise the Nordland and Hordaland shale sections, there is a risk ofdifferentially sticking the drill-string when drilling the Palaeocene sand section.

Prior to drill the sands, the mud system should be treated with 20 kg/m³ BARACARB 50and 9 kg/m³ BARACARB 150 (Graded Marble) as bridging agents. Maintain theconcentration of material in the mud by adding 1 sack of BARACARB 50 and 1 sack ofBARACARB 150 per stand, while drilling the sand to ensure enough fresh material isavailable for bridging. BARACARB will effectively bridge opposite the porous sand andminimising the filter cake build-up, filtrate/whole mud invasion, seepage losses anddifferential sticking.Mud samples should be sent to town on a regular basis to check the bridging effectivenessby measuring the particle size distribution of the fluid.

- Water phase salinity: It is recommended that the WPS is run at 160 g/l Cl-. Based on theoffset well data on blocks in the area, this level of salinity will mean that the shale arestabilised without taking so mush water into the mud and having to adjust the SWR.

Starting with 160 g/l Cl-, adjustments will be made as dictated by cuttings integrity andindications of water gains from the formation by way of osmosis.

- Alkalinity: the alkalinity should be maintained in the range of 10 - 15 kg/m³. Depletionand/or acid gasses may necessitate regular additions of lime to maintain this level.

- Solid control: It is essential that the maximum use be made of all available solids controlequipment. Run the shale shakers utilising the finest mesh screen possible. Ensure that

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Shale shaker screens are being effectively usedby analysing the LGS/HGS ratio in both the

input and output. Sand blinding has been experienced on the most of the surroundingwells, hence the selection of shale shaker screen sizes will be critical to avoid any surfacelosses of this expensive mud system. It is recommended that 120 mesh be used initiallyand as soon as possible they should be changed for 145/165.

However this should be reviewed in the light of mud properties and the nature of thesolids on the screens at the time. Shale shakers have to be attended to at all times, andscreens changed as circumstances dictate to keep the optimum screen size on the shakers.It is also suggested that both oblong, square and pyramidal screens be available on the rigsite and various combinations are tried to minimise sand blinding. The base fluid washgun should be available prior to drilling the 17 ½“ hole.

- Synthetic Oil on Cuttings: For the DTI Department of the Trade and Industry the SOCSynthetic Oil on Cutting are to be performed every 300 metres or daily, whichever is thesooner.The average quantity of oil on the cuttings for each well must be kept under 10%.i. cuttings samples will not be taken while coring.ii. cuttings samples will not be taken while drilling cement.iii. prior to take a cuttings sample, the shakers must be washed down with a high pressure

oil gun.iv. if the retort analysis gives a figure in excess of 120 g/kg, the procedure must be

repeated using a different sample to con firm the high value.v. cutting sample will be taken from the shakers only.vi. cutting sample must be retained for onshore analytical analysis.reporting of the SOC must be issued daily and a cumulative SOC will be issued at the endof each phase and at the end of each wells.

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3.3.5 Experience :

NOTIFICATION

Environmental concerns are now taking priority over technical or economical considerations in theselection of drilling mud systems for off shore uses. This trend is corroborated by the increasinglystringent regulations governing the amount of oil allowed to be discharged into the sea with drilledcuttings.On the 1/1/2001, a zero discharge limit will be imposed in the North Sea, with a four years transitionresulting in a reduction of 20% per year of the tonnage of oil wet cuttings discarded to the sea, basedon the 1996 year quantity.

This regulation preclude or limit the use of oil base mud or force that drilled cuttings be :• transported on shore and treated to remove adhering oil.• grounded and slurryfied off shore and injected in a dedicated formation through a disposal well. Facing this scenario much efforts has gone to improve water based mud, but the drillingperformances remain lower compared to those obtained while using oil base muds and PDC bits. BAROID have carried out extensive research into alternates to low aromatic mineral oil mudsystems. The outcome of these researches was the development of the Petrofree invert emulsionsystem which exhibits equivalent properties to mineral oil base mud without the environmentalinconveniences. The Petrofree shows very good bio-degradation properties, and due to this matter itsdischarge to sea had been allowed. This mud was first used in the years 1990 but it is very costly ( £ 1,200.00 m³ ) :• 5 time the cost of a low toxic oil base mud.• 2 to 3 time the cost of an synthetic oil base mud.ELF has been very reluctant to use this mud due to its cost.

For the Elgin and Franklin developments the 17½ sections are drilled from 900 m to 3800 m withinvert oil base mud. The first 2000 m are drilled in three days resulting in the generation of 1200tons of oil wet cuttings. It is impossible to recover and store on the rig this amount of cuttings for onshore or off shore process, so they must be discarded to the sea.

Due to the Elf Strategy for reducing oil discharge submitted to the D.T.I and the transition period fordischarge of oil wet cuttings by using an Ester base oil , it has been decided to run for the first timein the Elf group the Petrofree mud system from BAROID.

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1 Type of mud.

Type Used RecommendedXP07 or Petrofree XP07 or Petrofree

2. Density.A density of 1.55 SG provided good hole support.( vertical hole )

Density Used Density Recommended if angle> 35°1.55 SG 1.60 / 1.65 SG

3. Contingency stoks .Barite, LCM and ester stocks should be reviewed with the Elf supervisor prior starting eachsection. It is recommended to continue to keep these minimum contingency stocks for eachfuture 16” section.

Barite LCM F/M Base Fluid

Starting Stock 326 MT 30 MT 207 m3

Minimum Contingency Stock 150 MT 3/3 MT 150 m3

4. RheologyThe average yield point was in the 25 to 35 lb/100 sq. ft. range. No tight hole attributable topoor hole cleaning was seen.

PV YP Yield stressUsed 32 to 54 17 to 55 7 to 15

Recommended A.L.A.P 20 to 35 12 to 15

5. Emulsifiers and HPHTDue to the high efficiency of the mud cooler, lower then previously seen mud temperatureswere recorded, resulting in slightly lower rates of evaporation.As a consequence, less water was added to the mud but additions of emulsifier to the systemwere essential to maintain a stable mud system. The electrical stability was kept at 600-800volts with concentrations of EZ MUL NTE between 40 and 60 Kg/m3.

Primary Emulsifier Electrical StabilityUsed EZ MUL NTE 380 to 885

Recommended EZ MUL NTE > 400

HP/HT ml Temperature deg. CUsed 1.8 to 2.0 130

Recommended < 4.0 130

6. Alkanility

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XP07 or PETROFREE does not require high alkalinity.

Excess lime kg/m3.Used 0.9 to 1.5

Recommended, engineers 2.0 to 3.0Recommended, program 4.0

7. Evaporation.Levels of evaporation, were low throughout the interval considering the down holetemperature. Again this is due to an efficient mud cooler.

8. Oil water ratio and water phase salinity.Base fluid / Water ratio Water Phase Salinity.

mg/l ChloridesUsed 69 / 31 to 75/ 25 128,134 to 176,942

Recommended 65 / 35 to 70 / 30 >160,000

9. Low gravity solids : ESTER applicationDue to the temperature related expansion properties of the PETROFREE system, care mustbe taken when running the retort. The sample must be allowed to cool to 20 degrees Celsiusand the weight of the sample at this temperature checked on the temperature vs. weight chart( obtained with DFG+). This temperature corrected weight is then used to calculate the trueLGS content of the mud.

True Low Gravity solids, kg/m3.Used 35 to 138

Recommended > 150 Kg/m3

10. Solids Control

Scalper Scalper No.1 N0. 2 No. 3 No. 4 No. 5

Mesh size used atstart.

12 20 125125100

125125100

125125100

125125100

125125100

Mesh size used atend

12 20 185185145

185185145

185185145

185185145

185185145

Recommended atstart.

12 20 949494

949494

949494

12012094

12012094

Changing to :- 12 20 185185145

185185145

185185145

185185145

185185145

11. Base Fluid on Cuttings.

Interval average 80 /90 gm/kg

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10

The slow ROP and the PDC bits used in the bottom section of the interval produced smallcuttings resulting in a high arithmetical average for the Base Fluid On Cuttings. Data fromOILTOOLS.

12. 26” Cement drill out

The well was displaced to PETROFREE or XP07 mud after drilling out the cement withwater base mud. A good interface was seen on the displacement and the last two cubicmeters of water and the minimal interface was caught in the pits to minimise any risk ofspillage.

Drill out of cement.Displace to SBM only after good cement has been encountered.

Drill rest of cement with SBM.

13. Kill mud used.

Type & Weight Used RecommendedExploration well

Not required due to programme change. 50 m³ @ 1.75 SG

14. PIT ManagementNo problems were encountered with the pits due to the adequate volumes available. The pilltank should be left free of slugs so any pills / dilution can be made up. A separate pit shouldbe used for slugs.

RIG Selection :

The pit capacity is a major problem during this section , volume handle isaround 1000 m³ .

FRANKLIN 29 / 5b-F5 Hydraulics analysis - 17½" hole

02/05/1999 1025 1023 5.0 3390 146 112 4 9 x 16 5 31 25 1.60 27 1.61 31 41 54 27 18 1.05 Nordland

03/05/1999 1425 1422 2.0 3980 171 242 4 9 x 16 5 37 30 1.60 38 1.60 42 57 54 35 20 1.04

04/05/1999 1821 1817 5.0 4190 175 244 4 9 x 16 5 38 32 1.60 49 1.59+ 52 73 60 40 23 1.08 Hordaland

05/05/1999 2571 2539 25.0 4220 175 235 4 9 x 16 5 39 32 1.60 57 1.60 59 102 58 31 20 Hordaland

06/05/1999 2983 2900 29.4 4230 60 290 4 9 x 16 5 39 32 1.60 65 1.60 71 116 58 28 18 Hordaland

07/05/1999 3000 2915 4215 60 271 4 9 x 16 5 39 32 1.60 65 1.60 71 117 57 28 17 Hordaland

08/05/1999 3239 3123 26.1 4300 120 255 5 9 x 14 6 39 32 1.60 60 1.60 68 125 55 26 17 Balder

09/05/1999 3305 3182 25.3 3800 150 203 5 9 x 14 6 35 29 1.60 45 1.60 56 127 50 23 15 Sele - Lista

10/05/1999 3382 3252 22.5 3850 70 200 5 9 x 14 6 35 29 1.60 41 1.60 56 130 48 17 13 Lista

11/05/1999 3388 3258 3800 70 195 5 9 x 14 6 35 29 1.60 41 1.60 57 131 48 20 13 Lista

12/05/1999 3435 3435 4300 150 240 6 6 x 20 7 39 32 1.60 51 1.61 62 138 47 21 13 Andrew

13/05/1999 3462 3330 22.8 3870 110 170 6 6 x 20 7 36 29 1.60 57 1.60 65 133 44 20 12 Maureen

14/05/1999 3476 3343 3850 150 175 6 6 x 20 7 35 29 1.60 49 1.60 59 134 42 18 12 Maureen

15/05/1999 3482 3348 3800 110 190 7 9 x 16 8 35 29 1.60 43 1.60 54 134 47 20 14 Maureen

16/05/1999 3493 3359 3800 110 184 7 9 x 16 8 35 29 1.60 44 1.60 54 135 45 20 14 Maureen

17/05/1999 3502 3368 3850 110 197 8 4 x 22 9 35 29 1.60 40 1.60 55 135 45 19 12 Maureen

18/05/1999 3505 3370 3800 100 195 8 4 x 22 9 35 29 1.60 40 1.60 54 135 47 20 15 Maureen

19/05/1999 3524 3387 4050 60 266 9 1x16+3x20 10 37 30 1.60 46 1.60 60 136 47 23 14 Maureen

20/05/1999 3536 3398 4050 60 263 9 1x16+3x20 10 37 30 1.60 47 1.60 61 136 47 23 14 Maureen

21/05/1999 3542 3404 3700 60 218 10 1x17+3x20 11 34 28 1.60 47 1.60 62 136 46 24 14 Maureen

22/05/1999 3546 3408 4000 60 150 10 1x17+3x20 11 37 30 1.60 47 1.60 62 137 47 23 14 Maureen

23/05/1999 3546.0 3408 1.60 137 47 23 14

24/05/1999 3546.0 3408 1.60 137 47 23 14

25/05/1999 3546.0 3408 1.60 137 47 23 14

Page 1

Stand Pipe Pressure versus ECDEFLF on 29/5B - F5

160

175

190

205

220

235

250

265

280

295

310

325

340

355

370

385

400

415

430

445

1821 2271 2455 2850 3000 3200 3285 3370 3388 3405 3460 3475 3487 3493 3500 3505 3535 3546 3542Depth MD

Stan

d pi

pe P

ress

ure

17 1/2" Section

Flow rate value x 10 = l/min

SPP rig / ECDELF

DRILLING FLUIDS RECOMMENDATIONS

17½” – 16” Drilling section (910 to +/- 3500 m TVD)

PARAMETERS INDICATORS RECOMMENDATIONS / FIELD RESULTS - “RULES OF THUMB”- Remedial Action

Specific gravity

SG = 1.55 / 1.60

♦ Increasing of SolidsContents.

♦ Cavings on shakersup to 5% inHordaland.

♦ Large cavings afterside track in G8 wellat 40 degree angle

♦ Dilution with new mud.

♦ Drilled some wells in 16” (wells performed with Estersystem) to minimise the volume drilled.

! Necessity to have 850 m³ of new mud on board at thebeginning of section due to high ROP in shales.

♦ Use the finest screens possible (compatible with OOC) on theshakers to minimise mud contamination with solids.

! Good results.

♦ Maintain 1.55 SG mud weight, decrease flow rate to 4000l/min when ROP decrease.

♦ Increased mud weight to 1.60 SG to prevent caving indeviated well above 20-degree angle.

! Small amount of cavings during the section, decreasing at theend of section.

♦ Hordaland formation destabilised by water base cementspacer during side track. No mud solution: requested to sidetrack again the section just below the 20” casing, thus abovetop of Hordaland.

Rheology

♦ Hole Cleaning.

♦ PV: ALAP.

♦ Maintain a good carrying capacity with 4500 l/min Flow Rateand Yield Point > 30 by treatment with Geltone II / Suspen-tone + RM 63.

! Good result: no hole cleaning problems.

♦ Achieved by dilution with new mud, addition of EZMUL-2Fand solids control.

HT Fluid loss< 3/4 cc

♦ Increasing. ♦ Necessity to keep a low HP/HT filtrate due to a low-pressurezone in the Palaeocene: Kept Duratone HT concentration at14-16 kg/m³.

! HP/HT = 2.2 - 2.6 cc at 130ºC.

PARAMETERS INDICATORSRECOMMENDATIONS / FIELD RESULTS -

“RULES OF THUMB”- Remedial Action

Lime excess> 5/7 kg/m³ with

XP-07 system

♦ PB decreasing. ♦ Treat the active system continuously with Lime.

! No problems of mud stability in spite of an excess of Limesometimes less than 1 kg/m³.

ElectricStability

♦ > at 400 V. ♦ Kept a correct concentration of EZMUL-2F in the system tomaintain good mud stability in spite of water incoming fromthe formation (osmotic action on the shales) and wateradditions at surface to balance evaporation.

! ES at around 700 V at the end of section.

PalaeoceneFormation

Weak Zone

♦ Potentials FormationLosses.

♦ Differential Sticking.(2800 PSI overpressure)

♦ REMINDER

Shell Shearwater

♦ Before reaching the Palaeocene the Mud system will be treatedwith:

• Baracarb 150:10-15 kg/m³• Baracarb 50: 20-25 kg/m³• Baracarb 600: 1-2 kg/m³• Barofibre: 2-3 kg/m³• Soltex: 10-15 kg/m³

! Only some seepage observed.

♦ Kept a H/P H/T filtrate as low as possible as seen above.

! No differential sticking met in this section.

♦ Have a LCM pill (+/- 20 m³ with a concentration of 180 to 200kg/m³) ready to be pumped.

The HPHT fluid loss was maintained at less than 2 cc (<1 cc inmost cases) at the maximum geothermal temperature to minimisethe filter cake. This was maintained prior to entering the Palaeocenesands until the 14” x 13 3/8” casing was cemented.

To improve the quality of the filter cake, 70 kg/m³ cellulose LCMpills were spotted over the Palaeocene sands during connectionsuntil the bottom hole assembly was below the permeable sands.Prior to trip out of the hole, the same pills were pumped to cover thecomplete Palaeocene sands interval to prevent the formation ofthick filter cakes. The above measures proved effective inminimising the risk of differential pressure sticking as no signs ofdifferential sticking was observed during the six –well project.

PARAMETERS INDICATORSRECOMMENDATIONS / FIELD RESULTS -


Environment

♦ Oil on Cuttings. ♦ Optimisation of shakers screens.

♦ Use High G Dryer when available to return base fluid to thesystem and then minimise Oil Discharge to the sea.

Ø Kept Oil Content on cuttings less than 10%.

♦ Use time to time an Ester Mud System to drill section in orderto minimise the environmental impact of cuttings in the sea.

Ø Met problems of high rheology, gels and borehole instabilitywith this system on G8; system no more allowed to bediscarded with cuttings to the sea in 2002.

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3.5 14” x 13 3/8” casing and cementing

Running the casing: prior to run the casing, the gel strength and yield point must both bereduced, the yield point + 18 lb/100ft², and the 10’ gel to < 25 to avoid excessive surgepressures when running in. Pilot tests will be completed by the mud engineer to determinethe optimum treatment levels.

This can best be accomplished by additions of OMC 2 or by addition of base fluid. Careshould be taken so as not to over treat the system with OMC 2. When running casing,consideration should be given to breaking circulation half way in the hole, to reduce backpressure when breaking circulation on bottom prior to cementing.

Swab and surge calculations should be run on the actual data of the time to optimise therheological properties and casing running speeds, to ensure they are well within the limitsof the LOT at the 20” shoe.

- Synthetic base mud recovery: if no major problem of borehole stability has been seenwhile drilling, a sacrificial water base mud will be pumped to remove the SBM { Ester orXP07 }from behind the casing.

Recommended concentrations:

Drill waterSoda ash 0.75 kg/m3

Caustic soda 1.5 kg/m3

Bentonite 30 kg/m3

BARAZAN Plus 1.7 kg/m3

DEXTRID 7 kg/m3

BARASCAV D 0.75 kg/m3

ALDACIDE G 0.25 kg/m3

Barite to adjust density .

- Cementing job -

The 14” x 13 3/8”or 13 3/8” casing will be cemented with a lead and tail slurries.

The top of the lead will be around 2000 metres TVD ( See casing Load design ) . Thetop of the tail will be at 3050 metres TVD, to cover the Palaeocene sands.

A bottom and top plug cementing head will be used.

17 1/2” hole volume 155.2 l/mE.A. 17 1/2”x 13 3/8”: 64.4 l/mE. A. 20” (# 129.3) x 13 3/8”: 87.0 l/m

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12

13 3/8” inside volume: 77.24 l/mAnnulus volume: 263 m3

Synthetic Base Oil 5 to 10 m3

Sacrificial water base mud: 143 m3 Optional

Spacer volume: 25 m3

Lead slurry No excess 0 m3

Tail slurry volume 30% excess 15 m3

Displacement circa 288 m3

Fluid design:- spacer 1

Synthetic Base Oil 5 to 10 m3 (Has to be adjusted)

- spacer 2 : 15 / 20 m³

System Dowell Halliburton.Spacer Mud Push XL Spacer 500Viscosifier D149 Spacer 500Antifoam D144 NF5Surfactant U66 PEN5 & SEM7Barite

- Lead slurry mixed with Drill Water :

G cement (Dyckerhoff or Lafarge) Dowell Halliburton35 %BWOC Silica Yes YesBentonite Yes YesExtender D159 Silicalite 97Retarder D110 HR4

- Tail slurry mixed with Drill water :

G cement ( Dyckerhoff or Lafarge ) Dowell Halliburton35 % BWOC Silica Yes yesFluid Loss Control D143 Halad 100Antisettling D153 NoRetarder D110 HR4

Remark:- For an accurate displacement, the internal diameter of the casing must be measuredon 10% random joints.

Cement slurry properties:

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- Lead slurry

Density 1.65 SGYield 1445 l/tThickening time 10 - 12 hCompressive strength at BHCT >80 bar 24 h

- Tail slurryDensity 1.90 SGYield 996 l/tThickening time- 6-8 hCompressive strength at BHCT >170 bar 24 h

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3.6 Experience :Examining the practical aspect of cementing a 13 3/8” casing.

It is a detail procedure used to cement the casing with an ESTER mud .

This section gives preparation details and some recommendations for the 13 3/8" cement job. In order to achieve a good cement job and minimise the risk of contamination it ‘srecommended to perform the displacement of slurry with Petrofree and pumping a largesacrificial spacer ahead .

Current Well status :

TD for the Section : 3478mShoe Depth : +/- 3463m - Float collar : 3406m ( 5 joints )

Top Balder 3182 mTop Lista 3250 mTop Andrew 3294 mTop Maureen 3397 m

A : Centralisation for this casing should be as per following :

Diameter for centraliser : 16 1/8”OD for 17 1/2 ” hole

- 2 Solid SpiroGlider (16 1/8” OD ) per joint over the first four joints.

- 1 Solid Spiroglider ( 16 1/8” OD ) per joint from the float collar to the top of the tail slurry+/- 3000 m

- 1 Solid Spiroglider ( 16 1/8” OD ) every 3 joints from top of tail to 2000 m .

** - Marine Section from sea bed to well head :

1 Cast Centraliser 18” per joint ( internal clamp type ) installed Mid-joint , to be done on thedeckto minimise pause when approaching bottom .( see procedure Tie back on Elgin ref. UWG specif.E520 )

Note :- Special care for the installation and pass through the table .( Frank’s spider might be removedfor each centraliser )

Stand off : 72 % for this casing .

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B : Pre-job preparation :

1)Ensure all pits (to be used for the preparation of spacer and cement slurry mixwaters)[suggest one Reserve pit is used for the preparation of these water based fluids],mixing lines, circulation lines, transfer lines (including and especially the transfer lines fromthe pits to the Halliburton unit and cementing line to the rig floor are thoroughly cleaned outand flushed through with drill water .Check volume line between Rig floor and Halliburtonunit .

2)The 13 3/8” casing has been drifted and dimensionally controlled in order to better assessthe ID of the joints which will be used for the displacement calculation.

13 3/8” Average ID : 12.44 “ Volume = 78.40 l/mMud film removal = 1.665 m³

3 )The Halliburton or Dowell Batch Tank will be used for the Tail mixing water .( Capacity =23 m³ or 150 bbls )

Preparation of Spacer

4 ) The spacer ahead to be used is to consist of 14 m³ with Surfactant followed by 50 m³without surfactant of Spacer 500 weighted to 1.67 SG with Barite.

The cement spacer should be prepared in the dedicated pit during running of the casing asper Halliburton mixing instructions attached.. Check the rheology at room temperature at thisstage and compare to that achieved in the Halliburton lab.Weight up with barite to 1.67 SG (monitor throughout with a calibrated pressurised mudbalance), take a sample, check rheology, note result and compare it to the result achieved inHalliburtonl Lab and retain.The Surfactant should be added just prior to pumping downhole to prevent foaming i.e.directly into the Slug Pit.In the same time :

Prepare lead cement slurry mix water ( as per Cement recipe attached ) in a clean pit .Theretarder will be added once the circulation will be completed.Prepare in the Batch tank the mixing water for Tail slurry.(same recommendation for retarder ).

Once the freshwater has been added to the pit the chloride content of the freshwater should bechecked , the result noted and a sample of this water retained.

C :Running procedure and Fluid pumping Sequencee

Recommendations :

1 - In case of major problems ( abnormal drag ) , prior to entering the Palaeocene formationTop Balder another circulation could be done and the parameters established.( if necessary )

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2- According to the calculations, the down weight should be in the range of 340 T ( MartinDecker ) .

3 - Circulation prior to the job ( Annular volume +/- 225 m³ ) should be, at a minimum, 1.5times complete Annular Volume or entire casing contents. The flow rate will be graduallyincreased while monitoring for losses and cavings . Wait long enough during each step toassess the potential losses.

- Circulation through wellhead outlets to be done to remove potential cavings ( see F2 )

- Record pressure at bottom at different flow rates ( 1000 / 1200 / 1500 l/min )

- Losses reported on G7 ( 20 m³ during displacement )- Cavings were reported on previous wells ( F1& F2 )

D : Pumping sequence :

1 ) Pump Ester thin mud +/- 40 m³ at 1.65 SG with YP = +/-12 ( if possible )

2 ) Pump Spacer 1 , +/- 14 m³ at 1.67 SG with SEM 7 ( slug pit )

3 ) Pump Spacer , +/- 50 m³ at 1.67 SG without SEM 7.

4 ) Lead and Tail Slurry formulations as per Cementing receipe. The Volumes required are asfollows:

•Lead Cement slurry : Volume to fill annulus from 3100 m above the tail to 2000 m MD. NoExcess on Open Hole

Estimated volume : 75 m³ at 1.70 SG ; 75 Tons ( blended )

•Tail Cement Slurry : Volume to fill annular volume to 3100 m. above the 13 3/8" shoe plus theshoe track.Estimated volume : 32 m³ at 1.92 SG with 30% excess , 43 Tons ( blended )

Monitor density throughout mixing of both the lead and tail slurries with a pressurised mudbalance. Take a sample of both lead and tail slurry during mixing and check rheology in FannMeter.

5 ) Displacement with mud ( Petrofree ; SG = 1.65) Rig pumps at 1500 Litres/min. Monitorrates and pressures during the displacement and if losses occur, record the volumes, adjustingthe rates as required.

! 170 m³ @ 1500 l/min! 102 m³ @ 1000 l/min

Total displacement : 272.139 m³ ( to be adjusted according to the casing string diameter )

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ECD estimation before bump the plug : 1.76 EMW atTD ( 1500 l/min )

Surface Pressure before Bump : +/- 80 bars ( @ 800 l/min )Static pressure before Bump : +/- 30 bars ( low flow rate )

6 ) Bump plug and then pressure test casing to 160 bars .

( Plug ; Float collar & Cementing Head Pressure rating : to be checked )

Pressure Test casing will be done prior drilling out cement to 280 bars with mud at 1.30 SG ( to get 2.10 EMW at the shoe )

Timing :

Mixing + Injection Lead 90 minDisplacement N° 1 105 minDisplacement N° 2 107 minSafety factor 60 minTotal 422 min # 7 hours 12min

- All samples of fluids should be 1 litre in size.- Chloride content of Fresh water should be less than 500 mg/litre.

Thickening Time : TAIL Slurry : BHCT = 80 °C " 7 hours 20 mn @ 100 Bc

Compressive Strength : 2706 PSI 24 hours at 80 °C .

Thickening time : LEAD Slurry : BHCT = 80 °C "9 hours 12 min @ 100 Bc

Compressive Strength: 329 PSI after 24 hours at 80 °C.

E ) Wire Line Logging :

CBL to be done prior to drilling the next section .( +/- 24 hours after bump )The aim of this need is to check the top of cement in the annulus for safety factor requirementduring the production phase .The log will be recorded from +/- 2500 m to the Top of cement .

F ) ESTER displacement before resuming 12 ¼” drilling :

A spacer of Viscosified CaCl2 Brine could be pumped ahead of XP07 before drilling out thecement .30 m³ of Spacer seems enough to minimise the contamination of the ester . ( TBA in due time ) .Logistic with supply boat is the main problems to avoid any risk of contamination .

1

CEMENTING RECOMMENDATIONS

14” x 13 3/8” Casing set 50 m inside the TOR formation.

PARAMETERS INDICATORS RECOMMENDATIONS RESULTS / RemedialAction

TECHNICALCOLUMN DESIGN

♦ Cover the over-pressured Hordalandshales.

♦ Cover the potentiallyweak Palaeocenesands.

• Top of cement at 2000 m. TVD, typical excess 30%. • FIT at 13 3/8” above 2.00sg EMW

! Top of cement from900 to 2300 m

! No wet shoe, norestoration needed.

THICKENING TIME

BHST = 130º / 148 ° Cat bottom

BHST = 80 / 95°CAt the Top of Cement

BHCT Prediction :

A P I prediction : 96°C

Enertech: 80°C

Cemcade: 75° C

MWD record at TD indynamic conditions isaround 100°C

• Check the thickening time (T. T.) of Lead and Tailslurries at the maximum expected temperatureaccording to the simulation.

Slurry Design :• TT for Tail = 7 to 8 hours at 80°C. • TT for Lead = 9 to 10 hours at 80°C. Change in Thickening time values cement setting didnot have a pronounced effect on the set of cement atBHST

Thickening times: G4 - Lead 15 h 14 Tail 5 h 49 at 95ºCG5 - Lead 13 h 05 Tail 5 h 49 at 93ºC G6 - Lead 13 h 39 Tail 9 h 32 at 90ºC G7 - Lead 12 h 45 Tail 9 h 37 at 85ºC F1 - Lead 7 h 50 Tail 5 h 50 at 80ºCF2 – Lead 7 h 50 Tail 7 h 10 at 80ºCF3 – Lead 9 h 05 Tail 7 h 15 at 80ºC F4 – Lead 9 h 13 Tail 8 h 25 at 83ºCF5 – Lead 9 h 38 Tail 7 h 43 at 80ºCF6 – Tail 9 h 21 Tail 7 h 35 at 80ºC

COMPRESSIVESTRENGTH

Check the compressivestrength after 24 hours of

WOC

• For the tail the strength was checked at 110 °Caccording to the Enertech simulation after 24 hours ofwait on cement.

• For the lead slurry the strength was checked atthe BHST estimated at the top of cement (80 °C).

! 3000 PSI after 16hours

! 700 PSI after 22 hours

Samples set after 24 hours

at room temperature SLURRY DESIGN

G+35% silica

" Lead slurry :1.65sg

" Tail slurry : 1.92sg

♦ Slurry extender +fresh water

♦ Retarder:Dowell: 2.2 lit/tD110 Halliburton:0.3% to 0.5% HR4

• Gel with bentonite system is recommended andeasier to design.

Dowell:1.5 % BWOC of bentonite

Halliburton: 2.5% BWOC of bentonite • Adjust the TT to have the safety margin (+ 40%)

for the cement Job . The quantity of retarder isvery low then a special attention is necessary toprepare the mixing water .

! Lead mixing watermixed in a mud pit.

! Tail mixing water

prepared in the batchtank.

2


Sacrificial SPACER

Primary SPACER

♦ In case of use ESTER

♦ Compatibility withSBM and cementslurry.

• To recover mud behind casing for cost reduction

• 5 m³ of base oil + 5 m³ of chemical wash werepumped ahead to thin the mud.

• A volume of 20 m³ of spacer at 1.60sg with

surfactant was pumped ahead the lead slurry at1.65sg.

• Adjustment of the rheology on the rig

CAUTION :• Foaming after adding the surfactant.

It is essential that mixing procedures be adhered tothe recommendations done by contractor’s.

! No channellingreported.

! Spacer rheology hasbeen increased beforethe injection byreadjustment ofviscosifier.

Well Conditioning

♦ Pack off annulus withcuttings (see G5, F2)between theadjustable mudhanger and thelanding ring.

Circulation long way with correct mud parameters. Aclean annulus is requested before the job.

CBL - Top Cement ♦ CBL analysis

A CBL /VDL has been recorded to check TOC,generally the bonding is between 10 to 30 volts infront of the lead slurry. The top cement is clearlyidentified.

! G4 - TOC = 1720 m! G5 - TOC = 1720 m! G6 - TOC = 1470 m! G7 - TOC = 927 m! G8 - TOC = 2300 m

! F1 - TOC = 1815 m! F2 - TOC = 1700 m! F3 – TOC = 2275 m! F4 – TOC = 2107m! F5 – TOC = 2120 m! F6 – TOC = 1800 m

DISPLACEMENTCalculation

♦ Internal micrometerrecordings for 14 “and 13 3/8” casing,typical ID = 12.426”compared to 12.347”nominal ID.

♦ Mud compressibility.

♦ Rig pump

♦ Max volume

• This check is crucial to achieve a gooddisplacement of the slurry.

Average on 6 Franklin wells: the difference in volumebetween the nominal ID and the measured IDaccounted for +3.5 m³ on the displacementcalculation, this volume is equivalent to 45 m ofcasing.

• The extra volume due to the Hydrostatic columnof the fluid can be calculated but must not beincluded in the displacement. This volume on the6 wells on Franklin was + 3.7 m³ average, or 47m of casing.

• Displacement done with dedicated pump, rigpump efficiency (typically 97%).

• Do not over displace 50% of the shoe track.

! Bump the plug : OK

! Some losses werereported duringdisplacement.

Well 29/5b-F4Date

Top of cement (real) m 2000 (1815) 2000 (2120)Casing shoe m 3640 3532Height m 1145 495 1600 466 1100 364 1500 468 1032 500 1063 500BHST ºC 135BHCT ºC 80Type of slurry lead tail lead tail lead tail lead tail lead tail lead tailTheoritical slurry volume m³ 74 28 62 26 75 35 97 38 71 45 71 37Excess % 50 50 0 30 0 20 35 30 35 0 43 11Total slurry volume m³ 111 40 62.5 32.4 71 38 130 48 95 43 102 40Weight of cement (G+S) tonSlurry weight sg 1.65 1.92 1.65 1.92 1.70 1.92 1.65 1.92 1.65 1.92 1.65 1.92

Cement Lafarge G % 100 100 100 100 100 100 100 100 100 100 100 100Silica flour % 35 35 35 35 35 35 35 35 35 35 35 35Water type Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh FreshAdditives 2.5% Bento 2.5% Bento 2% Bento 2.5% Bento 2.5% Bento 2.5% Bento

1 lit NF-5 1 lit NF-5l/ton 0.45% HR4 0.28% HR4 0.45% HR4 0.28% HR4 0.53% HR4 0.35% HR4 0.5% HR4 0.28% HR4 0.55% HR4 0.36% HR4 0.52% HR4 0.36% HR4or 0.5% Hal-100 0.5% Hal-100 0.5% Hal-100 0.5% Hal-100 0.5% Hal-100 0.5% Hal-100 0.5% Hal-100% 50 lit Sil-97L 50 lit Sil-97L 50 lit Sil-97L 50 lit Sil-97L 50 lit Sil-97L 50 lit Sil-97L

Thickening time (70BC) hr:min 07:50 05:51 07:50 07:10 09:05 07:15 09:13 08:25 09:38 07:43 09:21 07:35Compressive strenght 12 hr PSI 380 740 1400 870 (32 h)Compressive strenght 24 hr PSI 930 2300 870 2400 330 2700 600 4700 1100 (40h) 1100 940 (40 h) 2900Flow pattern laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminar laminarSpacer type Base oil / Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+

sg 1.60 1.62Plug type Bottom and top plugDisplacement type 2 plugs 1.60 sg mud

29/5b FRANKLIN - 17 ½" OPEN HOLE / 13 3/8" CASING CEMENTATION

29/5b-F1 29/5b-F2 29/5b-F3 29/5b-F5 16" open hole

25/05/199930/03/1998 21/07/1998 24/10/1998 15/02/19992000 (2107)

3968

136

2 plugs

83

2 plugs

2000 (2275)3464

13080

1.67 1.62

158194148

80130

120

2 plugs

95

1400 (1700)3466

13080

1.60

29/5b-F610/12/19992000 (1800)

3563

Bottom and top plug1.61 sg mud

13580

150

1.62

m 3.97 3.07 2.03 1.92 2.5 2.48m 3572.68 3398.73 3398.17 3890.58 3464.68 3501.25m 3467.68 3398.73 3268.17 3440.58 3327.68 3457.25

in. 12.44 12.42 12.44 12.43 12.419 12.404 12.426l/m 78.41 78.16 78.41 78.29 78.15 77.96 78.23m³ 280.5 265.9 266.6 304.7 271.0 273.2m³ 278.0

∆∆ m³∆∆ % 0.0% 0.7% 0.6% 0.4% 0.6% -0.1% 0.4%

Yes Yes Yes Yes Yes Yes

in. 12.347 12.347 12.347 12.347 12.347 12.347 12.347l/m 77.25 77.25 77.25 77.25 77.25 77.25 77.25m³ 276.28 262.77 262.65 300.68 267.82 270.65

∆∆ m³∆∆ % -1.5% -1.2% -1.5% -1.3% -1.2% -0.9% -1.3%

XP-07 Ester Ester XP-07 XP-07 XP-07g/l 1.56 1.56 1.65 1.63 1.60 1.61m³

m 3640 3466 3464 3968 3532 3563.3

m³ 2.7

Nominal casingID size

Casing IDmeasurements

Casing ID measurements mud Compressibility

Landing collar

Top plug

- 3.5 m³

+ 1.0 m³

+ 4.7 m³

TEMPERATG4 Chart 4

Page 1

17 1/2" Temperature Prediction - ELGIN /FRANKLIN

0

20

40

60

80

100

120

140

160

1110 1448 2027 2730 2930 3091 3139 3160 3182 3209 3211 3292 3320 3360 3402 3440 3475 3550 3600 3610Depth TVD

Tem

pera

ture

in °C

Enert. BHSTGeol.BHSTMWDTemp in °CTemp out°CMud Cooler Mud Cooler

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4. 12 ¼” SECTION

Interval: +/-3900 m MD to +/-5300 m (MD)Max expected BHP: 1.80SG EMW.Expected temperature: 176°C BHST at 5100 m TVD BRT.

4.1 PurposeSet the 9 7/8” casing at the top of the Rodby ( circa 5050 m TVD BRT ) above the highpressure transition zone.

4.2 Drilling procedureRun in hole with 12 ¼” bit, drill out cement, the rat hole and 5 m new formation. Perform aleak off test (minimum expected 1.85 SG EMW, limited to 2.15 SG EMW).Drill ahead to drop off point. POOH and pick up the drop off assembly to obtain 0.5degree/ 30 m. Drill ahead.Run and cement 10 ¾” x 9 7/8” casing.

4.3 Expected problemsLoss/Gain situation:The transition zone below the Upper Cretaceous is thin and over-pressured.The 12 ¼” section must be stopped at the top of the Rodby but loss/gain situations couldoccur towards if the transition zone is too deeply penetrated.

4.4 Drilling fluids – Experience – HydraulicSynthetic base mud at 1.55 SG from the 17 ½“ section will be used to start drilling.The density will be adjusted to 1.35 SG to start and gradually increased to 1.65 SG around4500 m TVD BRT (circa 400 m TVD above the transition zone).

4.4.1 Typical composition of mud (1.65 SG, 75/25 OWR)

XP-07 (Base Fluid) 482 l/m³EZ MUL 2F (Primary Emulsifier) 48 l/m³Lime (Ca(OH)2) 11.5 kg/m³DURATONE HT (Fluid Loss Control) 43 kg/m³Water 159 l/m³GELTONE (Viscosifier/Gelling Agent) 3 kg/m³Calcium Chloride (CaCl2) 99 kg/m³Barite (Weighting agent) 742 kg/m³RM 63 (Rheology Modifier) 3 l/m³

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Weight : 1.55-1.65 SGPV : ALAP, typically 30-45 cPoYP : 18-20 lbs/100ft²YS : 8 - 10 lbs/100ft³Gels 0/10 : 10/12 - 28/32Filtrate API : 0 ccFiltrate HP/HT : 3.5 - 4 ccE.S. : > 400 VCl-(Water Phase Salinity) : 200 g/lH/E : 70 /30 - 75/25Excess of Lime : 0.5 – 0.7 g/l

4.4.3 Safety stocks

Bulk material

Barite : 150 tCement G + Silica Flour : 100 t

Material in sacks or drums

BARACARB 50/150 : 3 t / 3 tLIQUID CASING : 3 tChemicals to mix 300 m3 of synthetic base mud

Kill mud / Synthetic Base Oil

Kill mud 1.95 SG : 50 m³Base Oil : 150 m³

4.4.4 Recommendations

Hole stability and mud weight. The mud weight must be gradually increase to 1.65 SG toreach the Rodby marker. The transition zone is in the Rodby, Sola, Valhall, Kimmeridgeclays where the pore pressure increase sharply from 1.40SG EMW to 2.09 SG EMW.There is uncertainties on the top of formations, therefor the mud must be prepared for amajor increase in density without major impact on other mud properties. Pilot testingmust be done daily on a weight up to 2.00SG.

Hole cleaning. Optimise the cleaning of the hole through conventional rheology adjustingthe yield stress to 8-10 lbs/100sqft and with the maximum feasible pump rates (3,600 -

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4,000 l/min) . If necessary pump high viscositycleaning pills. The following points were raised for the 17 ½” section and are stillrelevant in this section:

• Use the highest possible pump output/annular velocities, do not circulate at less thandrilling rates circulation.

• Keep the Yield Point at 50°C between 18 and 22 lbs/100ft² with the Plastic Viscosity

as low as possible, typically below 45 cPo. • Optimise the low shear rheology using RM 63 and GELTONE II to assist in hole

cleaning by maintaining the Yield Stress between 10 and 12. • Maintain high initial gel strength 10 to 12 lbs/100sqft giving rapid suspension of

cuttings when the pumps are off during surveys, or trips. This should be combinedwith flat gel strength development.

• Use mechanical means (e.g. wiper trips, pipe rotation, reciprocation, back reaming

with the top drive if available, etc.) and weighted pills pumped prior to trips to assistwith hole cleaning.

• If a more viscous mud is required, suggest initial treatment to raise Yield Point to ± 25

and initial gel to ± 15. • If further viscosity increases are deemed necessary to improve the mud carrying

capacity, increase the Yield Point and 6 RPM reading in increments of 5 lb/100ft². 30should be considered the upper limit to ensure optimisation of the hydraulics.

• Even with mud properties and flow rates optimised a hole cleaning problem may still

occur. At the first indication of possible problems, pump a high viscosity/weighted pill(pump these pills prior the trips). This should be sized to cover 100 m of annular hole.It is recommended that a 2.0 SG weighted pill be pumped around while rotating thestring > 150 rpm if possible. In the case of all pills, do not stop or reduce thecirculation rate before the pill(s) have been evacuated from hole. To do so will resultin material dropping out of the pill and possibly avalanching downhole. All attemptsshould be made to isolate weighted pills on surface for re-use. Return of all pillsshould be monitored at the shakers, to gauge their effectiveness.

• The trend in the correlation of cuttings generated and seen at the surface to ROP can

provide another indication of the effectiveness of hole cleaning. The mud engineersshould be monitoring cuttings volumes and correlating with these drilling rates at alltimes. The shaker hands should also be shown what to watch for so that they canprovide a speedy warning e.g. a soft sticky must means the cuttings are being regroundin the well and are not being removed.

Seepage losses : Maintain the concentration of the bridging material at 20-25 kg/m3 to

effectively seal the formation, through the addition of BARACARB 50 and BARACARB

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150. Monitor the effectiveness of treatmentwith a Permeability Plugging Apparatus fitted with 40 micron aloxite disc.

Water phase salinity : It is recommended that the WPS is run at 200 g/l Cl-. adjustments

will be made as dictated by cuttings integrity and indications of water gains from theformation by the way of osmosis.

HPHT fluid loss. To be measured at 160°C. HPHT fluid loss must be maintain from 3.5 to

4 ml all oil, and with no API fluid loss. The filter cake must effectively seal the formationpreventing differential sticking and seepage losses.

Alkalinity. The lime content must be maintained in the range of 0.5 – 0.7 kg/m³. Depletion

and/or acid gasses may necessitate regular additions of lime to maintain this level. Sagging. Barite subsidence can take place in deviated wells. Monitoring of the start of

circulation must be done thoroughly. • The derrickman measures the specific gravity and the temperature of the mud with a

pressurised mud balance every 15 minutes, until the bottom-up reaches the surface. • The mud logger records the lagged depth versus the time until the bottom-up reaches the

surface. Note: do not rely on mud weight measurements from the mud logging company as most ofthe devices used are not accurate, when cold and viscous mud are processed. The mudweight must be recorded manually by the derrickman. • The mud engineer plots a graph of SG corrected at 50°C versus lagged depth and he

records separately:i. mud weight of mud before circulating.ii. rheology, gels of mud at end of last circulation.iii. maximum mud weight recorded while circulating.iv. minimum mud weight recorded while circulating.v. time spent while circulating.

Barite sagging handling procedure:

• Prevent the subsidence of barite adding 4 to 8 kg/m3 SUSPENTONE, anti-saggingagent.

• Avoid excessive treatment by thinners OMC 2, defloculants and excessive dilution. • Decrease the particle size distribution of the weighting material in running fine screens

on the shale shakers along with running the centrifuge at a low bowl speed. Note that alarge addition of barite will increase the sag. This is attributed to the presence of acoarse fraction in barite ore, which becomes progressively screened out.

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• Drilling practices: if the subsidence of baritecannot be eliminate, then the mud must be circulate on stage, while running in to thebottom to decrease the length of heavy mud in the annulus.

Temperature at flow line (±±±± 85°°°°). Towards the end of the section, temperature will behigh causing steam evaporation carrying oil vapours. Sufficient water will have to beadded

daily to maintain the oil water ratio in the range. In case of drastic increase in thetemperature, use the mud coolers.

Hydraulics. Plastic viscosity must be maintained as low as reasonably possible. PV at30cPo would be ideal (with maximum at 45 cPo) to promote low ECD EquivalentCirculating Densities.The ECD and ESD will be calculated using the ELF software along with FANN 70 data.Therefor a sample of mud must be sent to town at least twice a week for analysis. Thissample will to be stirred 2 hours in a high shear mixer, before starting any measurement.

Solid control equipment. It is essential that the maximum use be made of all availablesolids control equipment. Run the shale shakers utilising the finest mesh screen possible.Ensure that Tertiary equipment are being effectively used by analysing the LGS/HGSratio in both the input and output.The Creteaceous is quite inert and the selection of shakers screens will be based on fluidproperties and OOC figures. 140 to 165 meshes could be used in the upper part withattempt to size down the shakers to 165 to 200 meshes.Shale shakers have to be attended to at all times, and screens changed as circumstancesdictate to keep the optimum screen size on the shakers. It is also suggested that bothoblong, square and pyramidal screens be available on the rig site and variouscombinations are tried for optimum performance. The base fluid wash gun should beavailable to clean the screens.

Synthetic Oil on Cuttings: For the DTI Department of the Trade and Industry, the Mudengineers performs the SOC on a composite sample every 300 metres or daily, whicheveris the sooner. The mud engineer also collect all statutory samples while using syntheticoil base mud.

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4.4.5 Experience :

Recommendations :1. Type of mud.

Type Used RecommendedXP-O7 - synthetic based mud XP-O7 - synthetic based mud

2. Density

A density of 1.30/1.35 SG provided good hole support and improved penetration by approximately10%. The mud was weighted up at 4,800 metres.

Density Used Density Recommended1.30 to 1.60 SG 1.30 to 1.60 SG

3. LCM Contingency.The requirement to have higher stocks of BARACARB for contingency stock was met from thestart of this well. It is recommended to continue to keep this minimum contingency stock for eachfuture 12 ¼” section.

BARACARBBarofibre / C Steelseal 50 / 150 / 600

Starting Stock 2 / 2 tonne 3 tonne 4 ½ / 2 ½ / 2 TMinimum Contingency Stock 3 tonne F 3 tonne M

4. RHEOLOGY.A yield point of 15 - 20 gave adequate hole cleaning properties. The average was 18 lb/100 sq.ft. A 6 rpm reading of 10 - 12 was adequate for a hole angle of 38.8 degrees inclination asmeasured by the lack of hole problems while drilling or during trips. No tight hole attributable tocuttings beds or poor hole cleaning was seen.

.PV YP 6 rpm

20 -32 15 - 20 10 -12Recommended A.L.A.P 15 - 20 8 - 12

5. EMULSIFIERS and HPHT.

The HPHT test temperature was raised from 130 ºC to 160 ºC at 4,900 meters.

Primary Emulsifier Electrical StabilityUsed EZ MUL 2F 400 - 600

Recommended EZ MUL 2F > 400HPHT, ml. Temperature deg C.

Used 1.6 - 3.0 130 / 160Recommended < 3.0 - 4.0 130 / 160

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6. ALKALINITY.

Continue to use lime to maintain an adequate alkalinity.

Excess lime kg/m3.Used 3.0 - 6.0Recommended, engineers 5.0 - 10.0Recommended, program < 5.0

7. EVAPORATION.Levels of evaporation,averaged about 5 m3 per day. The rate of evaporation was in the 0.75-1.30% range.

8. OIL WATER RATIO and WATER PHASE SALINITY.

Water additions were required to maintain the O/W in the upper half of the interval. Evaporationwas used to increase the O/W in the lower half of the interval towards 80/20. Evaporationnecessitated water additions to maintain the O/W ratio.

Oil / Water ratio Water Phase Salinity.mg/l Chlorides

Used 70 / 30 - 79 / 21 160,000 - 225,000Recommended 70 / 30 - 75 / 25 - 80 / 20 160,000 - 200,000

9. LOW GRAVITY SOLIDS.

No centrifuge was available.

Low Gravity solids kg/m3.Used 20 - 116

Recommended < 175

10. SOLIDS CONTROL.Scalper Scalper No. 1 N0. 2 No. 3 No. 4 No. 5

Used at start. 20 20 185 185 185 185 185Used at end. 20 20 185 185 185 185 250

Recommended at start. 20 20 150 150 150 150 150Changing to : NA NA 185 185 185 185 250

11. Base Fluid on Cuttings.

The slow ROP in the bottom section of the interval produced small cuttings resulting in a higharithmetical average for the Base Fluid On Cuttings.

Interval average 14 / 15 gm/kg

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12. Cement Drill out

Drillout of cement.Use the XP-O7 mud to drill out the cement.

13. KILL MUD USED.

Type & Weight Used RecommendedXP-07, 50+m3 XP-07, 50 m3

1.95 SG 1.95 SG

14. PIT MANAGEMENT.

No problems were encountered with the pits due to the adequate volumes available. The pill tankshould be left free of slugs so that pills or dilution can be made up. The pit used for kill mud canthen also become the source of heavy slugs.

FRANKLIN 29/5b-F3 Hydraulics analysis 12 ¼" hole

01/11/1998 3479 3397 1.9 3500 80 270 6 4 x20 8 79 64 1.30 54 1.30 76 20 12 10 1.04 Claystone02/11/1998 3608 3459 1.9 3500 190 270 6 4 x 20 8 77 62 1.30 56.8 1.30 63.9 20 12 9 1.04 FAIL03/11/1998 3642 3492 1.9 3500 110 258 6 4 x 20 8 80 65 1.31 58.9 1.30 67.7 21 12 13 1.0404/11/1998 3648 3498 1.9 3500 175 258 6 4 x 20 8 1.31 1.31 21 12 13 1.0405/11/1998 3907 3827 1.9 3500 200 270 7 9 x 13 9 81 25 1.31 58.7 1.31 66.2 25 14 14 1.04 Fail06/11/1998 4155 4073 1.9 3500 200 274 7 9 x 13 9 82 25 1.31 65.9 1.31 73.1 23 15 14 1.04 Fail07/11/1998 4405 4326 1.9 3500 200 280 7 9 x 13 9 82 25 1.31 63 1.31 73 23 14 14 1.21 Fail Fail Limestone08/11/1998 4650 4570 1.9 3500 200 280 7 9 x 13 9 82 25 1.45 66 1.45 73 32 14 15 1.40 Fail Fail09/11/1998 4868 4785 1.9 3500 200 295 7 9 x 13 9 79 24 1.61 67 1.61 73.2 38 20 18 1.49 Fail Fail10/11/1998 4957 4875 1.9 3500 200 295 7 9 x 13 9 74 23 1.60 65.8 1.60 73 36 18 16 1.50 Fail Fail11/11/1998 5065 4980 1.9 3250 200 260 7 9 x 13 9 75 23 1.60 65.4 1.60 73.4 38 18 16 1.50 Fail Fail12/11/1998 5160 5077 1.9 3250 200 260 7 9 x 13 9 75 25 1.60 67 1.60 74.3 40 16 17 1.50 Fail Fail

Hydr. sum. F5-12 ¼

FRANKLIN 29/5b-F5 Hydraulics analysis 12¼" hole

29/05/1999 3546 3406 23.0 3180 60 276 11 3 x20 12 73 50 1.30 43 1.30 55 133 21 1130/05/1999 3555 3414 23.0 3240 63 286 11 3 x 20 12 74 51 1.30 42 1.30 51 134 28 1631/05/1999 3596 3452 23.0 3220 91 280 11 3 x 20 12 74 51 1.30 44 1.30 55 135 22 1401/06/1999 3626 3481 23.0 3240 120 280 11 3 x 20 12 74 51 1.30 45 1.30 56 135 22 1602/06/1999 3657 3509 23.0 3240 115 283 11 3 x 20 12 74 51 1.30 44 1.30 58 136 26 1803/06/1999 3698 3550 19.1 3260 175 291 12 9 x 13 13 75 51 1.30 47 1.30 56 137 24 1704/06/1999 3730 3580 18.6 3230 139 290 12 9 x 13 13 74 51 1.30 46 1.31 56 138 28 1505/06/1999 3857 3702 16.4 3250 190 291 12 9 x 13 13 75 51 1.32 52 1.32 62 142 29 1506/06/1999 4081 3918 13.2 3250 195 305 12 9 x 13 13 75 51 1.36 48 1.34 60 148 31 1607/06/1999 4081 3918 14808/06/1999 4128 3965 12.2 3225 127 313 13 9 x 13 14 74 51 1.38 45 1.37 56 149 28 1709/06/1999 4215 4050 11.57 3230 160 309 13 9 x 13 14 74 51 1.38 48 1.39 59 152 30 1509/06/1999 4279 4113 3230 160 314 13 9 x 13 14 74 51 1.38 52 1.39 59 154 36 1710/06/1999 4394 4223 10.6 3220 160 309 13 9 x 13 14 74 51 1.38 50 1.39 58 157 30 1511/06/1999 4606 4434 9.1 3240 156 313 13 9 x 13 14 74 51 1.39 48 1.39 60 163 33 1512/06/1999 4800 4627 7.4 3230 155 305 13 9 x 13 14 74 51 1.42 55 1.42 65 169 32 1612/06/1999 4824 4650 7.2 3200 154 324 13 9 x 13 14 73 50 1.47 51 1.46 66 169 39 1713/06/1999 4925 4750 6.9 3020 158 306 13 9 x 13 14 69 48 1.56 55 1.56 61 172 34 17

4951 4775 7.0 3030 154 309 13 9 x 13 14 69 48 1.60 46 1.61 61 173 34 1714/06/1999 4990 4815 6.8 3030 159 325 13 9 x 13 14 69 48 1.61 47 1.61 61 174 37 1615/06/1999 4990 4815 17416/06/1999 5186 5009 6.3 3020 157 310 14 9 x 13 15 69 48 1.60 50 1.60 60 180 33 1917/06/1999 5280 5102 6.2 3030 170 320 14 9 x 13 15 69 48 1.60 50 1.60 63 182 36 1418/06/1999 5280.0 5102 14 9 x 13 15 1.60 50 1.60 60-68 35 1519/06/1999 5280.0 5102 14 9 x 13 15 1.60 35 1520/06/1999 5280.0 5102 35 1521/06/1999 5280.0 5102 35 1522/06/1999 5280.0 5102 35 1523/06/1999 5280.0 5102 35 1524/06/1999 5280.0 5102 35 1525/06/1999 5280.0 5102 35 1526/06/1999 5280.0 5102 35 15

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Hydr. sum. F5-12 ¼

FRANKLIN 29/5b-F5 Hydraulics analysis 12¼" hole

29/05/1999 3546 3406 10 1.06 Maureen30/05/1999 3555 3414 14 1.0631/05/1999 3596 3452 11 1.06 Ekofisk01/06/1999 3626 3481 12 1.0602/06/1999 3657 3509 11 1.0603/06/1999 3698 3550 10 1.06 1.31 Tor04/06/1999 3730 3580 10 1.06 1.3105/06/1999 3857 3702 10 1.06 1.3206/06/1999 4081 3918 11 1.06 1.3407/06/1999 4081 3918 1.0608/06/1999 4128 3965 10 1.06 1.3709/06/1999 4215 4050 10 1.07 1.38 Hod09/06/1999 4279 4113 11 1.08 1.3910/06/1999 4394 4223 10 1.1911/06/1999 4606 4434 10 1.3212/06/1999 4800 4627 11 1.3812/06/1999 4824 4650 12 1.3913/06/1999 4925 4750 11 1.42

4951 4775 11 1.4314/06/1999 4990 4815 10 1.4415/06/1999 4990 481516/06/1999 5186 5009 11 1.45 Herring17/06/1999 5280 5102 1118/06/1999 5280.0 5102 1519/06/1999 5280.0 5102 1520/06/1999 5280.0 5102 1521/06/1999 5280.0 5102 1522/06/1999 5280.0 5102 1223/06/1999 5280.0 5102 1524/06/1999 5280.0 5102 1525/06/1999 5280.0 5102 1526/06/1999 5280.0 5102 15

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DRILLING FLUIDS RECOMMENDATIONS

12 1/4” Drilling section (+/- 3500 to +/- 5040 m TVD)

PARAMETERS INDICATORS RECOMMENDATIONS FIELDS RESULTS

Specific Gravity

• Increasing SolidsContents

• ROP • Gas Shows

♦ Use fine shaker screens to remove maximum

of solids drilled from the mud.

♦ Start section with 1.30 / 1.35 SG instead of1.55 (mud weight at the end of 17½” section)then adjust the mud weight according to thegas shows.

♦ BAROID DFG+ Software used to correct

density to 50ºC. ♦ Increase SG to 1.60 / 1.62 before reaching the

transition zone, then before Casing running,the Mud weight could be adjusted to 1.70 SG.

♦ The anticipated maximum mud weight is 1.70SG although barite stocks should be carried toallow an increasing of SG to 2.15.

! OK as long as Oil

On Cuttings stayscompatible withEnvironmentalregulation.

! ROP increasing by10%

! Consistent stabledensity at 50ºC.

! Good stability of

mud! Back ground gas <5

%

Rheology

• YV > = 20 • PV > = 35 / 45 • Yield Stress >7 / 9

♦ Due to a significant ROP in the TOP section a

YP of 20 /25 is recommended.♦ Keep PV ALAP by addition of EZMUL and

adjustment of O/W ratio to 75/25 at the end ofsection

♦ Maintained with RM 63, Suspentone andGeltone II.

! No impact on the

ECD! No Hole cleaning

problems have beenreported.

! Well in goodcondition

HP/HT Fluid Loss < 3 /4 cc

• Increasing

♦ Keep DURATONE HT concentration at 14 / 16

kg/m³ with a treatment of 300 kg/day.♦ Add Invermul 2F towards end of section.

! Kept HP/HT = 2.6

to 2.4 cc at 160 °C! HPHT at 180ºC at

end of section.

Lime Excess

> 2/4 kg/m³

• PB (Pom)

Decreasing

♦ System treatment of 1 to 2 tons/day of Lime.

! Kept Lime excessbetween 1and 5kg/m³.

! No problems ofstability

! E S = 850 V at theend of section

2

PARAMETERS

INDICATORS

RECOMMENDATIONS

FIELDS RESULTS

Treatment to startthe section

• Rheology and mud

weight adjustment

♦ Need a dilution of 20% to reduce Mud Weight

from the previous phase.♦ Mud treatment with Geltone II in order to keep

a good rheology.

! Need space pit! Adjust OWR to

75/25

HYDRAULIC

ECD - ESD

• Stand Pipe pressure • L.O.T / ESD • Potentials Losses • Differential sticking

♦ Run software to follow trend ESD and ECD ♦ Run PWD. Good relation between Pressure

readings and simulated.♦ ECD = 1.41 SG at 4606 m for a mud weight of

1.38 @ 50°C and a flow rate 3240 l/min. ECD= 1.58 SG at 4805 m for a mud weight of 1.55@ 50°C and flow rate 3030 l/min.

♦ Work with minimum mud weight compatible

with gas background.

! Good prediction ofESD & ECD fromECDELF.

! Good correlationbetween the predic-tions and the SPPon the rig. (Ex:Estimated = +/-260bar, on Rig Site =259 bar)

! No differentialsticking

Gellation due tothe Temperature

Overpressure to

break gels

Temperature

SAGGING

• Gel 30 min

increasing • PWD tool

interpretationindicates 149°CBHCT at TD

• Density return

REMINDER

♦ Mud treatment with primary Emulsifier / Lime /Geltone / Duratone HT in order to maintaingood concentrations in the system.

♦ A sign of SAG was detected after one extendedflow check at 5130 m. After treatment withSUSPENTONE no further sag indications werereported.

♦ Mud should be treated with 3-5 kg/m³Suspentone during this Interval

! Gels 0/ 10 /30 min:14 / 26 / 30

! Overpressure to

break gels = 55 PSIafter 48 hoursbefore resumingcirculation.

! BHST (StaticTemperature) 180/185 °C at the endof section(correlation withEnertech + drillingdata)

Well bore Stability• No Wiper trip at the

end of section. • No Wiper trip before

running casing.

♦ Same mud formulation and maintenance isrecommended for the next well

! Good Stability! Run Casing: 10¾”

x 9 7/8” withoutproblems.

3


Evaporation

• Loss of water , OWRincreasing

• Gellation

• Fluid loss up

• Run Mud Cooler when mud temperature outreaches 70°C.

• • An addition of 200 / 1000 litres / hour of drill

water is recommended during drilling orcirculating.

• Addition of EZMUL-2F as primary emulsifier is

required to replace the emulsifier lost with theevaporating water.

• Treatment with DURATONE HT.• INVERMUL 2F additions towards end of

section for HPHT at 180ºC.

! Kept temperature at50°C in and 60°Cout.

! Maintained OWRat 75/25

! HP/HT between2.6 and 2.4 cc.

Pollution

Environment♦ Target for 12 ¼”:

8% ( Oil on cuttings)

• Dead volume in mud pits: (See 17 ½”comments).

• Solids/mud discharge from the centrifuge / High

G Dryer: The use of fine screens on the shakerswill prevent the use of the centrifuge.

• Coarser screens• Screens of 200 mesh or finer • The solids discharge would drop into a screw

conveyor to a recovery system supplied by STSto a Skip or Big Bag station, and be sent ashorefor disposal in the Future according to the ELFStrategy.

• Waste Disposal tank should be supplied by ELF.

! OOC=+/-10.9 % ! No centrifuge

required. ! Lower O.O.C.! Poor solids

distribution, loss ofDuratone, increasein HPHT.

! No oil spills werereported .The slowrates of penetrationproduced smallcuttings resulting ina high arithme-ticalaverage for theOOC.

LOGISTIC SAFETY STOCK

VOLUME

♦ Stocks and Volumes

• Keep on board 300 m³ of mud to anticipate therisk of transition zone.

• LCM stocks levels.

! XP-07 base fluid:for 150 m3 of mud.

! Chemicals: for150 m3 mud.

! 50 m³ Kill Mud:1.95 SG.

! Barite in bulk: 150tons (then 400 tonsat the end ofsection).

! BARACARB-50:3 tons.

! BARACARB-150:3 tons.

! Barofibre /Steelseal: 3 tons.

4


TYPICAL

CHEMICAL

CONCENTRATION

END OF SECTION

• SG = 1.66

• OWR = 77 / 23

♦ XP 07 Base oil = 550 litre/m³♦ Drill water = 160 litres/m³

♦ Barite = 700 kg/m³♦ CaCl2 brine = 19.69 litres/m³♦ Lime = 39.94 kg/m³

♦ EZ MUL 2F =45.36 litres/m³♦ Duratone HT = 11.7 kg/m³♦ Geltone 2 = 4.5 kg/m³♦ RM 63 = 3.42 kg/m³♦ Suspentone = 3.71 kg/m³♦ Baracarb-150 = 8.5 kg/m³♦ Baracarb-50 = 14 kg/m³♦ Baracarb-600 = 1.5 kg/m³♦ Barofibre = 2.2 kg/m³♦ Soltex = < 7 kg/m³

COST

• Budget : £

♦ Good behaviour of XP07 mud system .Mudspecifications in line with the program.

! Average Cost : +/-

xxx £ / m³

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4.6 10 ¾ “ x 9 7/8” casing and cementing

Option N°1 :In the nominal case the 10 ¾” – 9 7/8” casing will be run as a single string and must becemented up to 200 metres above the X-over 9 7/8” x 10 ¾” installed above the 13 3/8”casing shoe .

Option N°2 :If hole conditions dictate there is the option to run the 9 7/8” casing as a liner with a 10 ¾”tie-back casing .The casing string is a tapered of 10 ¾” (110.2#) by 9 7/8” (66.9#) casings( Liner ).

- A temporarily Uncemented 10 ¾” tie back will be run after the cement job of the 9 7/8”Liner after displacing a CaCl2 / CaBr2 brine in the 13 3/8” x 10 ¾” annulus before thereconnection of the Tie-Back . The brine will be treated with corrosion inhibitor andbactericide .

- Or the Tie-back will be Cemented up to 500 metres above the receptacle by .

For the single string “ HP HT “ Bottom and top plug cementing head will be used .( supply by ODDCC , see drawings )

Running the Casing. Prior to run the casing, the gel strength and yield point must both bereduced, the yield point + 15 lb/100ft², and the 10’ gel to < 23 to avoid excessive surgepressures when running in. Pilot tests will be completed by the mud engineer to determinethe optimum treatment levels.This can best be accomplished by additions of OMC 2 or by addition of base fluid. Careshould be taken so as not to over treat the system with OMC 2 that can cause baritesagging or settling.

Swab and surge calculations should be run on the actual data of the time to optimise therheological properties and casing running speeds, to ensure they are well within the limitsof the LOT at the 13 3/8” shoe.

Cementing jobThe 9 7/8” casing will be cemented with lead and tail slurries ( 400m of tail slurry ).

Fluid design :

! spacer 1: Preflush 0.76 SG. – Chemical wash 3 to 5 m3 ( Has to be adjusted with Surfactant )

! spacer 2: Spacer at 1.70/1.75. YP/PV 25/40.

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Contractor Dowell Halliburton Spacer Mudpush XTO Spacer 500E+ Viscosifier 16 kgs/m³ 20 kgs/m³ Surcactant U66 - 47.6 l/m³ SEM7 - 80l/m3

Barite for density Defoamer as required

! - Lead slurry, retarded and extended 1.75 SG – VOLUME = Theoritical + 20%

G cement Dowell Halliburton Dyckerhoff Lafarge Silica 35 % Bwoc 35% Bwoc Fluid loss D143 – 1% Halad 100 - 0.5% Extender D145 – 7l/T Silicalite - 50 l/T Bentonite 1.2 % 1.5 % Retarder D161 – 84 l/T HR12 – 0.12% Drill Water 681 l/T 659 l/T ! Tail slurry: gas tight 1.92 SG. - VOLUME = Theoritical + 20%

G cement Dowell HalliburtonDyckerhoff Lafarge

Silica 35 % Bwoc 35% BwocFluid loss D143 – 1% Halad 100 - 0.75%Extender D145 – 7l/T Silicalite - 90 l/TRetarder D161 – 60 l/T HR12 – 1%Drill Water 473 l/T 478 l/TDispersant B78 – 3.1l/T CFR3 – 0.5%

Remarks:1. all the formulations are indicative, they must be confirmed by laboratory testsperformed with samples coming from the rig before the cement jobs. 2. For an accurate displacement, the internal diameter of the Casing must bemeasured on 10% random joints.

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Cement slurry properties :

! Lead slurry Density 1.75 SG. Yield 1280 l/t Thickening time > 12 h Fluid loss < 150 ml Free water 0 % Compressive strength at BHCT > 100bar 48 h

! Tail slurry

Density 1.92 SGYield 997 l/tThickening time 9 hFluid loss < 40mlFree water < 0 %Compressive strength at BHCT >200bar 24 h

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4.7 Experience :

This programme is an example issued prior each cementing operation .

Purpose :Set a 10 ¾” x 9 7/8” Casing just above the Base Cretaceous Unconformity ( the transitionzone ).The goal of the cement job is to realise a good shoe integrity , obtain 100% DisplacementEfficiency by using laminar flow with a synthetic base mud , pressurised and tested theproduction casing to 863 bars { 12525 PSI } after the bump with ODCC HP/HT plugs.

The following are some recommendations for the 10 3/4”x 9 7/8" cement job on G8 well :A - Current Well status :12 ¼” open hole 5512 m MDBRT

Shoe Depth : 5500 m MDRT ( 12 m of pocket )

Float collar : 5464 m MDRT ( 3 joints )

Landing collar : 5320 m MDRT ( 15 joints above the shoe )

Top of cement +/- 3340 m MDRT ( 200 m above XO 9 7/8” x 10 ¾” @3540 m )

GeologyTop Hod 4553 m ( 4035 m TVDrt )Top Herring 5298 m ( 4756 m TVDrt )Top Plenus marl 5437 m ( 4895 m TVDrt)Top Hidra 5440 m ( 4898 m TVDrt)Top Rodby 5520 m

B - Centralisation for this casing must be as per following :

Casing Configuration :1 shoe joint .2 joints ( Baker locked )1 float collar joint12 joints ( Baker locked )***1 landing collar joint .( ODCC)* The aim is to obtain +/- 200 m of shoe track- 2 Solid SpiraGliders ( 9 7/8” x 12” OD ) per joint over the first Five joints. 1 Solid SpiraGliders ( 9 7/8” x 12” OD ) per joint from the float collar to the top of the

landing collar- 1 Solid SpiraGliders ( 9 7/8” x 12” OD ) per two joint from the L C to the X-over 10 ¾”x 9 7/8”

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-1 Solid SpiraGliders ( 10 ¾” x 12” OD ) per two joint above the X-over 10 ¾”x 9 7/8”to 3340 m

The calculated stand off of the casing is above 85 %. From TD to 5000 m and 64 % above

C - Pre-job preparation :

1) Ensure all pits (to be used for the preparation of spacer) [suggest transfer and slug pitare used for the preparation of this water based fluid], cementing line to the rig floor arethoroughly cleaned out and flushed through with fresh water.

2) The casing was drifted and dimensionally controlled in order to better assess the ID ofthe joints which will be used for the displacement calculation .

10 ¾” 110.2# Average ID: 8.715“ Volume = 38.49 l/m9 7/8” 66.9# Average ID: 8.624” Volume = 37.67 l/m

Reference :( G5 = 37.7 l/m -G7 = 37.68 l/m - G6 = 37.57 l/m - F1 = 37.60 l/m - F2 = 37.8 l/m )3) Check HP/HT plug and cementing head ( ODCC equipment )- Note : Installation of the plugs inside the cementing laborious , a special concern to

install the bottom plug with the bar in ( risk of damage of the “ O “ ring seal ) .Check the valves .

Note : Back up Option for Cementing Head if not available on time - Dowell “9

5/8” cement Head + X-over 10 ¾” Vam with ODCC Plugs installed see drawing - 4) Tally ( length , composite casing , colour code etc … ) , see appendices

Preparation of Spacer : Mud Push XTO or Spacer 500 E+

The spacer consists of 25 m³ of Spacer MudPush XTO ( see Dowell formulation ) weightedto 1.70 SG with a yield point of 17 / 20 @ room temperature.Once the freshwater has been added to the pit the chloride content of this water should bechecked, the result noted and a sample of this water retained. Take a sample of spacer whencomplete, measure rheology at mix + temperature , note result and retain.( compare with theformulation )

Note : Rheology of spacer not in conformity with the laboratory results , adjustment ofchemical on the rig site .YV =13

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D - Running procedure and Fluid pumping Sequence

Break circulation at the 13 3/8” casing shoe to establish parameters. Circulate 10 / 20 minsat 1500 l/min record weight up & down .

Note on G7 : Break circulation with 20 bars at 566 l/min after 37 hours .Note on G5 : Break circulation with 45 bars at 1150 l/min after 36 hours .

Note on G5 : Due to the elevated weight of the casing the running speed has been adjustedto avoid shocks in drilling line drum .( the water cooling hose was replaced on draw works )

Note on F1 : At 4902 m Draw work fail to lift casing due to the clutch slipping - Cool downclutch with air & water .

- According to the calculations, at bottom, the string weight should be ± 660 metric tons.( or 1,455,026 lbs)

Note on G7 : Up Weight : N/A - Down weight : 574 tonsNote on G6 : Up Weight : N/A - Down weight : 565 tons ( with 300 mof casing empty )Note on G5 :Up weight : 627 tons - Down weight : 582 tons .Note on F1 :N/A - Down weight : 630 tons .( with 1500 m of casing empty, Differentialpressure max on float equip ment = +/- 2500 PSI )Note on F2 : ran casing with 1500 m of casing emptyNote on F3 : ran casing with 1500 m of casing empty – Up weight 570 T , Down weight540 TNote on F4 : ran casing with 1500 m of casing empty – String weight 475 TNote on F5 : ran casing with 1500 m of casing empty – String weight prior to land 495 T

- Circulate last joint and land casing hanger ( +/- 2 m stick up ) - Install XO + Cementing head .

The casing has not to be reciprocated close to the landing shoulder . If we need to pick upto cure a pack off at the casing hanger then pull out inside the riser and circulate ( seeVETCO manual ).

- Break circulation slowly and check surface pumping pressure at previously establishedrates Whilst running in the hole with 10 3/4”x 9 7/8”, select 1 high pressure mud pump andcheck seals , liners .

Note on G5 : No circulation to reach the casing depth ( no Fill )Note on G6 : No circulation to reach the casing depth ( no Fill )Note on G7 : No circulation to reach the casing depth ( no Fill )-Flow =1700 l/min ,P = 138 bars

Fluid pumping sequence :

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Circulation prior to the job should be , at a minimum, 1.5 times complete Annular Volumeor entire casing contents (whichever is the largest). The flow rate will be gradually increasedwhile monitoring for losses.

The maximum flow rate will be 1700 l/min.

G5 : Break circulation with 30 bars after 60 hoursF1: Break circulation with 36 bars after 61 hours .G6: Break circulation with 35 bars after 63 hours .F2: Break circulation at bottom @ 1500 l/min - SPP = 124 bars .F3: Break circulation at bottom @ 1500 l/min - SPP = 119 bars .F4: Break circulation at bottom @ 1500 l/min - SPP = 138 bars .F5: Break circulation at bottom @ 1200 l/min - SPP = 110 bars .

E - Cementing Operation :Mix and Pump

1) - 50 m³ of low rheology ( PV=33 , YV = 5 - Gel 10 = 20/25 ) mud at 1.60 SG ahead of spacer .2) - 25 m³ of Mud Push XTO at 1.70 SG ahead of cement slurry .U66 as surfactant3) - Pump CHEMICAL wash ( 5 m³) from Dowell displacement tank ( DW + 47.6 l/m³ of U 66 )4) - Drop after the Bottom plug .

5) - Slurry formulation as per attached Dowell Fax.The Volumes required are as follows:

- Lead Cement Slurry : Volume to fill open hole annular volume + 20% excess , TOC = 3340 m .

Estimated volume :Annulus volume 45 m3Excess 30% + rathole 171/2 ” 10 m3

Total Lead : 55 m3 at 1.75 SG

- Tail Cement Slurry :Volume to fill open hole annular volume to 5000 + 20% excess on open hole + FC / shoe track .

Estimated volume :Annulus volume : 14.8m3Excess 2.9 m3Shoe/FC 6.78 m3

Total Tail: 25 m3 at 1.92 SG

The tail slurry mixing water will be mixed inside the Dowell batch tank .Monitor density throughout mixing of tail slurry with a pressurised mud balance.

Take a sample of the slurry during mixing and check rheology.

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6) Drop Top plug.

7) Displace (RIG Pumps) with SBM mud ( @ 1.60 SG ) at 1500 litres/min reducing the flow to+/- 500 l/min before the bump ( +/- 45 bars ∆P differential pressure) and bump the plug.

Note G5 : See Shearing Bottom plug to 3700 PSI instead 2200 PSINote F1 : See Shearing Bottom plug to 3140 PSINote G6 : See Shearing Bottom plug to 2100 PSINote G7 : See Shearing Bottom plug to 2428 PSINote F2 : See Shearing Bottom plug to 2714 PSINote F3 : See Shearing Bottom plug to 2771 PSINote F4 : See Shearing Bottom plug to 3714 PSINote F5 : See Shearing Bottom plug to 2928 PSI

ECD estimation before bump the plug : EMW at TD ( at 1500 l/min )ECD estimation before bump the plug : EMW at TD ( at 250 l/min )

Surface pressure before Bump : ± 1300 psi ( at 450l/min )

Surface pressure before Bump on F1 : 1142 PSI at 470 l/minSurface pressure before Bump on G6 : 580 PSI at 500 l/minSurface pressure before Bump on G7 : 571 PSI at 500 l/minSurface pressure before Bump on F2 : 628 PSI at 500 l/minSurface pressure before Bump on F3 : 928 PSI at 500 l/minSurface pressure before Bump on F4 NO BUMP : 1371 PSI at 500 l/minSurface pressure before Bump on F5 : 714 PSI at 500 l/min

NOTE : If no bump , limit over-displacement to 150 m of the +/- 200 m shoe track .Bottom plug Shearing = 2200 PSI Theoritical TBA

DISPLACEMENT : 207 m³ including compressibility of 50% of the Hydrostatic mud column.( Theoritical displac. :203.306 m³+ 3.595 m³ = 206.901 m³ )

F - Casing Pressure Test :

1)Bump plug to 210 bars ( surface pressure ) and hold for 5 mins . Check floats holding .Pressure up to 450 bars to latch the HP/HT ODCC plug for 5 mins then remove XOand cementing head .2) Make up HP Circulating head and pressure test casing to 12525 PSI ( 863 bars ) for 15 minutes (stabilised )

Pressure test will be done by step ( 300 / 500 /600 /800 /900 bars , i.e )( Note : mud compressibility => 3.08 litre / m³ / 1000 PSI with 1.63 SG)

or 4.45 litre / m³ / 100 Bars

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On F1 : volume pumped to reach High pressure = 7.552 m³ .On G6 : volume pumped to reach High pressure = 8.427 m³ .On G7 : INCIDENT : Stop test due to leaking packing on DOWELL UNIT - Repair –

Test Positive to 873 bars .Bleed off volume = 8.100 m³ .On F2 : volume pumped to reach High pressure = 7.960 m³ .On F3 : volume pumped to reach High pressure = 8.100 m³ .On F5 : volume pumped to reach High pressure = 8.020 m³ .

3) Remove HP head , disconnect + retrieve hanger r/tool and continue with Vetco wellheadprocedure .( flushing tool …etc..),

Notes: - All samples of fluids should be 1 litre in size.

Temperature Estimation :

BHST New APIBHCT

CemcadeBHCT

EnertechBHCT

180 ° C 154° C 130 ° C 125 ° C

PWD : ( drilling .3100 l/mn at 5500 m) == > 157 ° C at 5500 m .

Thickening Time :Tail Slurry : BHCT = 130 °C " 9 Hour 34 min

Compressive Strength at 160 °C" 3650 PSI after 24 hours

Thickening time ;Lead Slurry : BHCT = 130 °C " 12 hours 52 minCompressive Strength at 130 °C " 700 PSI after 24 hours .

General note on high pressure testing of production casing strings on plug bump (HPHTwells)

Advantages• If the casing design is suitable the casing can be tested in its entirety to a higher pressure than when

the cement is set (the back-up pressure in the cemented section is much lower than the hydrostaticpressure of a column of mud and green cement).

• The internal and external pressure profiles are known (cement still in a liquid state)• Unlike pressure testing with the cement set, there is no risk of damaging the cement bond.• It can be cost effective by eliminating the time required to make staged pressure testing with a

packer.• There is no risk of damaging the casing with a packer (packer slips damaging the inside of the

casing).• If the casing is tested after the cement is set the wing valve of that casing annulus is normally left

open. If the casing should fail while pressure testing there is a massive shock on this annulus and ahigh pressure fluid surge through the bleed-off line from the wing valve - this has a potential todamage the well and to shock any un-secure lines from the wing valve.

Drawbacks• If the float equipment fails there is a potential to washout the cement in the shoe track and around

the shoe. To avoid this the shoe track volume must be at least equal to the compressed volume ofthe fluid inside the casing while pressure testing (on our HPHT wells we commonly use 20 joints inthe shoe track).

• If barite fallout is assumed in the production casing annulus then the pressure differential achievedon plug bump is not normally sufficient to achieve the same differential pressure as a gas to surfaceload. However, it can be argued that in a gas to surface case the ballooning of the production casingwould increase the pressure in the production casing annulus to offset the loss in hydrostaticpressure due to barite fallout.

EquipmentTo date we have used ODCC high pressure landing collars for our production casing strings:Production String Max surface pre

bumpCirc T (appro

static TNumber of Comment

10 3/4” - 9 7/8” prod cs 900 bar 155°C / 185 7 All successfu10 3/4” tie-back 950 bar 100°C / 125 4 Note 1.7” - 7 5/8” tie back 932 bar 155°C / 185 2 Note 21. One failure attributed to not slowing down sufficiently for the plug bump.2. One failure when the bottom plug landing was incorrectly interpreted as the top plug landing and

failing.

Note:• Both of the failures above occurred on early HPHT wells when the displacement volume was not

accurately known (no callipering of casing joints or allowance for fluid compressibility).• The tie-back landing collars have a poppet system which allows fluid to pass up through the landing

collar after the top plug has landed (other wise the tie-back seal assembly could not be stabbed intothe tie-back receptacle due to compression of the trapped fluid).

• On most of our wells we normally bring the pressure up to 50% of the final bump pressure and wait15 minutes before bleeding off to install the high pressure swedge. The casing is then pressuretested to the full bump pressure required e.g. 900bars.

1

CEMENTING RECOMMENDATIONS

10 3/4” x 9 7/8” PRODUCTION Casing set into Hidra Formation


PRODUCTIONCOLUMN DESIGN Good casing integrity

• Obtain a good bond between casing andformation to prevent any influx through the casingannulus in optimising of the slurries placement,through the design of the fluid properties and theflow rate.

• Top of cement inside the 13 3/8 x 10¾” annulus

• Pressure test column to 900 bars.

§ All FIT compatible todrill reservoir, 2.30sg.

§ Good CBL in front oflead slurry but badresults in front of tailslurry. Still working onspacer properties.

§ TOC: 500 to 1000 mabove planned.

FLUIDS WEIGHT Determination

• To help displacement, the specific gravity ofspacer, lead slurry must be staged with at least 5points difference.Mud < Spacer < Lead Slurry < Neat Slurry.We finished drilling the section with mud at1.65sg, the spacer was 1.70sg, lead slurry at1.75sg and tail slurry at 1.92sgG.

• These weights have to be compatible with:- Pore pressure.- Fracturing pressure (losses).

§ Few formation lossesduring cement jobs

§ Found top cementabove planned depth.

SLURRIESTHICKENING TIME

♦ T.T. depends on theBottom HoleCirculationTemperature andthe pressure.

♦ BHCT estimatedwith severalmethods:

- API table- Enectech software- Cemcade sofware- MWD, PWD…

Founded several values of BHCT for a same BHST(ex: API 140°C, Enertech 120°C, Cemcade 125°C,MWD records 137°C, PWD 142°C for BHST 185ºC).• Check the T.T. of lead and tail slurries at the

maximum expected temperature according to thesimulation

• Control it at the others temperatures (including thecirculation temperature estimated at the top of leadslurry).

• Adjust T.T. to have a minimum safety margin of 2hours on the cement job timing.

Change in thickening time values of slurry did nothave a pronounced effect on the set of cement atBHST.

§ Lead slurries:G4: 7h52 at 140ºCG5, G6, G7: 10h15 to14h27 at 130ºC.Franklin: 9 h 15 to 12 h15 at 125ºC.

§ Tail slurries:

G4: 11h31 at 140ºCG5, G6, G7: 08h10 to9h18 at 130ºC.Franklin: 8h36 to 9h37at 125ºC.

COMPRESSIVESTRENGTH

♦ Check C.S. after 24

hours of WOC

♦ Check C S at top ofliner

• For the tail the C.S was checked at the simulatedtemperature (Enertech) after 24 hours of WOC.

• For the lead slurry the C.S was checked at the

BHST estimated at the TOL (125 °C).

§ Tail: 2600 PSI after 24hours at 125ºC

§ Lead: 1000 PSI after40 hours

Samples set after 36 hoursat room temperature

2

PARAMETERS

INDICATORS

RECOMMENDATIONS

RESULTS / Remedial

Actions

SLURRIES DESIGN

♦ Lead slurry 1.75sg

♦ Tail slurry 1.92sg

• A slurry with bentonite (1% BWOC) isrecommended and easier to design than a slurrywith polymer as extender.

• To avoid dehydration of slurry in front ofpermeable formations and prevent any gas influx,reduce fluid loss of tail slurry below 150cc withfiltrate reducer as D143, D134 or Halad 100.

• Adjust the TT to have the safety margin (+40%)

for the cement job with retarder (D161 or HR12).The quantity of retarder in mixing water is crucial,so special care must be taken to calculate thequantity required and to measure it.

§ Due to the largevolume required, thelead mixing water hasbeen mixed in a mudpit.

§ Tail mixing waterprepared in the batchtank. No use of LAS.

§ NO MAJORPROBLEMS FORMIXING.

§ Additives to besupplied in drums.

SPACERS

♦ Spacer design

♦ Rheology

♦ Compatibility withSBM and Cement.

• On the first wells we used an emulsified spacer(15m³ oil/water based) pumped just after a pill ofbase oil (3m³) then followed by lead and tailslurries.Later on, due to the bad quality of the mudremoval, we changed:- the pill of base oil by a pill of thin mud (40m³)- the type of spacer, using a 100% water basedspacer with surfactant, to help bond betweenFormation/Cement/Casing.

• Adjust fluid rheology in order to have Mud <

Spacer < Lead Slurry < Tail Slurry in wellconditions.

• Check Rheology under high temperature to avoidany settling.

• Rheology sensitivity test with blends at:5 / 10 / 20 / 50 / 75 / 100%.

§ Better quality ofdisplacement on thelast wells than the firstones.

§ Still better quality ofCBL in front of LeadSlurry than Tail Slurry.Only on F3 well, wenotice a good CBLbelow the landingcollar. The cementsheath above thelanding collar had beendamaged by thepressure test at 900bars of the column, 2hours after pumping theslurry. Creation of amicro annulus.

SLURRY VOLUME

♦ Lead to 200 m above13 3/8 casing shoe

♦ Tail: 400 above10 ¾” shoe

• Cover the X-over 10 ¾” x 9 7/8” with slurry

Ø Typically 10% excess

§ Lead 30 to 46 m³

§ Tail 21 to 34 m³

DISPLACEMENT

♦ ID from Micrometer

typical measurements10 ¾” casing ID: 8.73” – 38.62 lit/m9 7/8” casing ID:8.617” – 37.63 lit/m.

♦ Rig pumps

♦ Check HP/HT ODCCplugs and modifiedhead to avoid topplug to remain inhead.

• This check is crucial to achieve a gooddisplacement of the slurries. Average on 4Franklin wells: the difference in volume betweenthe nominal ID and the measured ID accounted for+3.2 m³ on the displacement calculation, thisvolume is equivalent to 85 m of casing.

• The extra volume due to the mud compressibilityof the fluid can be calculated but must not beincluded in the displacement. This volume on the4 wells on Franklin was + 2.4 m³ average, or 63m of casing.

• Displacement done with dedicated pump, rigpump efficiency (typically 97%).

• Do not over displace 50% of the shoe track.

§ Shoe track: 220 m.

§ All placement: OK- Shearing bottom plug:

typical 200 bars.- Bumped plug: OK,

except F4 where thetop plug remained inthe head.

- Press. Test to 900bars: OK except F4.

Well 29/5b-F4Date

Top of cement (real) m 3250 (2275) 3762 (3272) 3258 (2840)Casing shoe m 5146 5425 5264Height m 1300 418 1282 420 1250 646 1238 425 1606 400BHST ºC 178 179 178BHCT ºC 125 125 125Type of slurry lead tail lead tail lead tail lead tail lead tailTheoritical slurry volume m³ 34.5 20.6 33.2 22.7 36 28 34.5 21.5 42.7 20.2Excess % 40 40 40 20 0 10 0 10 10 10Total slurry volume m³ 46.8 25 45 28 30 34 35.8 23.85 46.5 21.3Weight of cement (G+S) ton 84 33 41 30 41 43Slurry weight sg 1.75 1.92 1.75 1.92 1.75 1.92 1.80 1.92 1.75 1.92

Cement Lafarge G % 100 100 100 100 100 100 100 100 100 100Silica flour % 35 35 35 35 35 35 35 35 35 35Water type Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh Fresh FreshAdditives 1.5% Bento 1.5% Bento 1.5% Bento 1.5% Bento 1.5% Bento

1 lit NF 5 1 lit NF 5 1 lit NF 5 1 lit NF 5l/ton 1% HR-12 1.3% HR-12 1% HR-12 1.3% HR-12 0.7% HR-12 0.9% HR-12 0.85% HR-12 1% HR-12 0.93% HR-12 1.15% HR-12

or 0.5% Hal-100 0.75% Hal-100 0.5% Hal-100 0.75% Hal-100 0.5% Hal-100 0.9% Hal-100 0.5% Hal-100 0.75% Hal-100 0.5% Hal-100 0.75% Hal-100% 50 lit Sil-97L 90 lit Sil-97L 50 lit Sil-97L 90 lit Sil-97L 50 lit Sil-97L 90 lit Sil-97L 50 lit Sil-97L 90 lit Sil-97L 50 lit Sil-97L 90 lit Sil-97L

0.5% CFR-3 0.5% CFR-3 0.5% CFR-3 0.5% CFR-3 0.5% CFR-3

Thickening time (70BC) hr:min 10:45 09:20 11:05 09:37 09:15 08:36 12:15 08:36 11:22 09:26Compressive strenght 12 hr PSI 800 2800 1800Compressive strenght 24 hr PSI 3100 (48 hr) 3600 (48 hr) 1250 (48 hr) 3800 (48 hr) 860 3100 100 3300 130 2700Flow pattern laminar laminar laminar laminar laminar laminar laminar laminar laminar laminarSpacer type

sg 1.70 1.75 1.70Plug type ODCC HPHT ODCC HPHT ODCC HPHTDisplacement type 2 plugs top plug not realesed. 1.60sg SBM

Spacer 500E+

29/5b-F522/06/1999

29/5b FRANKLIN - 12 ¼" OPEN HOLE / 10 ¾ x 97/8" CASING CEMENTATION

12/03/1999

Spacer 500E+

29/5b-F120/04/19983400 (2492)

5118

ODCC HPHT2 plugs

29/5b-F322/11/1998

Spacer 500E+

ODCC HPHT2 plugs

29/5b-F211/08/1998

Spacer 500E+

3300 (2370)5002

183125

1.70

183125

Spacer 500E+1.70

90 77

4.9 Temperature Modelling

Experience from previous wells drilled has shown that drilling the bottom of the 12 ¼” section givesthe highest drilling fluid temperature at surface . The real data from 22/30 C - G 4 have been used tovalidate the results from the thermal model Enertech Wellcat which is become the standard forHP/HT applications .As a guide , the undisturbed formation temperatures can be taken as 194 °C for the Franklin sandsand 207°C at TD for the Pentland Formation .5 5/8” logging No 1 : Temp recorded = 200 °C

No 2 : Temp recorded = 199 °CNo 5 : Temp recorded = 207 °C ( to be confirmed on the next well )

The table below shows predicted temperature for one typical ( Drilling 8 1/2” ) using the thermalmodel Enertech Wellcat .

Well data : Depth = 5555 m MD ( 5413 m TVD ) - BHST = 184 °C -SG =2.17 - Flowrate = 1000l/min.

Parameters Well site ENERTECH

Bottom Hole StaticTemperature ( BHST )

184 ° C 184 ° C

Temperature IN 41 ° C 43 ° C

Temperature OUT 46 ° C 45 ° C

Bottom Hole Circ.Temperature ( BHCT )

** 147 ° C +/- 2°C 155 ° C

** PWD sensor

Bottom Hole mud Temperature

Temperature measurement while drilling has not been able to record with a good accuracy . A newdownhole PWD tool with temperature sensors has recently been developed to assist drilling of thereservoir section .During the Downhole hydraulics measurements tests after a close analysis weredone on the data recover from different sensors installed in the drilling string . It appears clearly thatthe 3 sensors are given same temperature values .These common values are very close to thetemperature of the mud inside the drill string .When using the RTPWD tool in real time mode , the temperature data sent to the surface andavailable while drilling is not the RTPWD temperature sensor reading but the temperature reading ofthe sensor located inside the telemetry module of the MWD assembly .

Therefore , in order to get accurate annulus Bottom Hole Circulating Temperature ( BHCT ) forusing on Hydraulic calculations and BHCT in cementing , it recommended to use the followingcorrection :

Take the real time Temperature sent to the surface ( telemetry module temperature ) = Ta

Subtract 2°C to get the internal mud temperature above the bit = Tb = Ta - 2°C

Add 7°C to get the annulus mud temperature = BHCT = Tb + 7°C = Ta + 5 °C

! BHCT = T a + 5°C

Recommendation :In any case measured BHCT will be cross- checked with the ELF temperature prediction software (WT-Drill from Enertech )

Safety & Mud cooler :On the previous wells drilled the highest drilling fluid temperature at surface was reported at thebottom of the 12 ¼” section which is not the case on G4 . The installation of Mud Coolers tominimise the temperature was incontestable due to the fact that the maximum temperature recordedwas only 61 °C compared to the flow line peak recorded between 76 - 83 °C .The use of mud coolingsystem during the critical section has been shown to reduce the flow line temperature by 10°C to15°C , leadind to a better working environment .

Wellcat Printouts show predicted temperature for 3 predominate drilling phase using Enertech .( see attachments )

Page 1

12 1/4" Temperature Prediction - Elgin / Franklin

0

20

40

60

80

100

120

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160

180

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2930 3095 3139 3160 3540 3600 3612 3756 3842 3896 3970 4008 4148 4236 4240 4329 4416 4565 4612 4665 4730 4817 4932 4940 4980 5000

Depth TVD

Tem

pera

ture

in °C Enert. BHST

MWDBHCT pred.Temp in °CTemp out°CMud Cooler Mud Cooler

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5. 8 ½” SECTION ( HP/HT section )

Interval: from +/- 5300 m (MD ) 9 7/8” shoe to +/- 6450 m (MD).Maximum expected BHP:

Lower Cretaceous 2.10SG EMWKimmeridge clay 2.10 SG EMWFranklin sands 2.11 SG EMWPentland 2.07 SG EMW

Expected temperatures:204°C BHST at 5900 m TVD.

5.1 Purpose:

Option 1:Drill and core 8 ½” hole through the remaining of the Cretaceous, the Upper Jurassic andthe top of the Middle Jurassic (Pentland formation) to 60m below the Franklin Sands.Requirement is to cover reservoir(s) and ensure a good isolation between Franklin sandsand Pentland.

Option 2:According to results of first wells it could be decided to develop the Pentland. In this case,two options are available:! Drill 8 ½” to 60m TVD below Franklin Sands, RIH and cement a 7” liner. Then drill 5

5/8” to 50m TVD above Bottom Pentland and set a 4 ½”.! Drill 8 ½” to 50m TVD above Bottom Pentland and set a 7” liner. In the case of

problem when drilling the Pentland reservoir, a 7” liner could be set below the FranklinSands. The Pentland would be drilled in 5 5/8” and cased with a 4 ½” liner.

5.2 Drilling procedure :5.2.1 GENERALITY :

Tag the cement. Increase the mud weight to 2.15 SG. Drill out cement, clean rat hole and 5 m. of new formation. Perform the LOT (expected 2.30 SG EMW, limited to 2.40SG EMW). Drill to ± 5m. above Franklin Sands. Coring of Franklin sands as programme . Drill 60 mTVD below Franklin Sands. Run logs. Drill ahead to TD, taking one core in the Pentland. Run and cement 7” or a tapered 7” x 4 ½” liner.

5.2.2 Hydraulic Tests : Reference : “DOWNHOLE PRESSURE & TEMPERATURE Measurements on 22/30 C – G4 “ Gelation tests while tripping in the hole:

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Purpose:

Obtain transient pressure data which characterizes the effect of mud gelation on flow properties.Also obtain surge/swab data with no flow. These tests are performed while RIH to exploit the factthat no circulation has occurred for a long period. The effect of pipe rotation on breaking mud gelswill also be studied. Drill pipe rotation during these tests will be minimal.

Surge tests while tripping: Purpose: Provide about 25 stands of surge data at varying speeds in hot, gelled up mudwhile tripping in the hole inside the 9 5/8” casing.

Gelation tests on bottom: Purpose: Obtain transient pressure data which characterizes the effect of mud gelation onflow properties. Also obtain surge/swab with no flow.

Circulation tests on bottom: Purpose: Obtain temperature and pressure data with time while circulation at differentflow rates through stationary drill pipe.

Surge/swab tests on bottom while circulating: Purpose: Obtain surge/swab data while circulation at a constant rate and with no flow.Circulation allows a quantitative measurement of return flow after the first surge.

Effects of rotation on circulating properties and a shut-in period: Purpose: Obtain temperature and pressure data with time while circulation at differentflow rates through rotating drill pipe. Two rotary speeds will be examined. Also monitortemperature build-up and any mud sag phenomena.

Swab tests while tripping: Purpose: Provide about 25 stands of swab data inside the 9 7/8” casing during normaltripping operations.

5.3 Expected problems : Mud weight control. The main problems are experienced whilst drilling through the

transition zone, when the pore pressure and fracture pressure are close, leaving little roomfor error in mud weight. The control of the mud weight is of a paramount importance.

• Fluctuation ESD (Equivalent Static Density) can be due to: - pressure variation, - temperature variation (from circulating profile to static profile).

• Fluctuation of ECD (Equivalent Static Density) can be due to: - flow rate variation - pipe movement, i. e. Rotation . Tripping in or out .

All this variation must be quantified to know exactly the pressure exerted by the drillingfluid. Failure to properly control the mud weight can lead to losses and gain instability.

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Differential sticking.

Differential sticking into the Pentlands reservoir can occur. The pressure required tocontrol the Franklin sands can be too high in front of the deeper reservoir.

Reservoir pressure and formation temperature.

• HP 1111 bars at 5364 m. TVD/SS.• HT 205°C BHST at TD.

H2S: Hydrogen Sulphide was encountered in the previous wells 30 to 50ppm during

testing. None was reported while drilling but over 4000 ppm were measured whilerecovering a core.

Barite sagging (see 12 1/4” section)

5.4 Drilling fluids – Hydraulic : Synthetic base mud at 1.65 SG from the 12 1/4 “ section will be weighted to 2.15 beforedrill-out of cement and perform the LOT

5.4.1 Typical composition of mud (2.15 SG, 85/15 OWR)

XP-07 (Base Fluid) 418 l/m³ EZ MUL 2F (Primary Emulsifier) 67 l/m³ Lime (Ca(OH)2) 20 kg/m³ DURATONE HT (Fluid Loss Control) 55 kg/m³ Water 75 l/m³ GELTONE (Viscosifier/Gelling Agent) 3 kg/m³ Calcium Chloride (CaCl2) 57 kg/m³ Barite (Weighting agent) 1515 kg/m³ RM 63 (Rheology Modifier) 1.5 l/m³ SUSPENTONE (Specialised Viscosifier) 4 kg/m³ BARACARB 50 (Bridging LCM Material) 30 kg/m³ BARACARB 150 (Bridging LCM Material) 6 l/m³

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Weight : 2.15 SG PV : ALAP, typically 40-55 cPo YP : 15-20 lbs/100ft³ YS : 8 - 20 lbs/100ft³ Gels 0/10’/30’ : 16/25/35 Filtrate API : 0 cc Filtrate HP/HT : < 3 cc @ 190 °C E.S. : > 800 V Cl-(Water Phase Salinity) : 225 g/l H/E : 80/20 - 85/15 Excess of Lime : > 1.5 to 2 g/l

5.4.3 Safety stocks

Bulk material:

Barite : 150 t Cement G + Silica Flour : 100 t

Material in sacks or drums:

BARACARB 50/150 : 3 t / 2 t Chemicals to mix 300 m3 of synthetic base mud

Mud / Base oil

Kill mud 2.45 SG : 50 m³ Liquid mud in surface : 250 m³ Base Oil : 75 m³

5.4.4 Recommendations :

Mud weight: Continue with the XP-07 system from the previous section, adjusting theoil/water ratio towards 85/15 and the weight to 2.15 SG with Barite before drill-out thecement. A mud weight of 2.15 SG will be required for this entire section. A portion of the above mud may have to be back-loaded to accommodate the volumeincrease caused by the weighing up and conditioning of the mud system.

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Mud weight measurement: Calibrate the Halliburton balance daily with Calcium BromideBrine and a Hydrometer. Temperature correction effects should be observed. Record mudweight and temperature at the flow-line and pits.

Temperature: Due to expected bottom hole temperatures greater than 200ºC, theemulsifier concentration should be raised to 67 l/m³, and the DURATONE HT added to aconcentration of 55 kg/m³ initially. The DURATONE concentration may require to beincreased in order to maintain the filtrate to required specification as the intervalprogresses.

Temperature and pressure calculations should be run before and during drillingoperations to analyse the effective change in downhole pressure cause by the heating,cooling and circulating of the mud system. Good ventilation is mandatory at the shale shakers and the pit room. The return mud atthe flow-line is likely to have a temperature in the range 60°C - 85°C, where a measure ofwater and oil evaporation will take place.

Seepage/losses/gain : Add 30 kg/m³ BARACARB 50 and 6 kg/m³ BARACARB 150 to the

mud system and 1 - 2 sacks per stand while drilling the sands to ensure that enough freshmaterial is available for bridging purposes. BARACARB will effectively bridge across the porous sands minimising filter cake build-up, filtrate/whole mud invasion, seepage losses and differential sticking. Follow good well control practices by carefully monitoring pit level and background gas. Direct treatment with base fluid and chemical to the active system will not enableaccurate pit level monitoring. All treatments to the active system should be to one of thereserve pits then added to the active mud. Pit levels may rise/fall (neither a kick nor downhole losses) due to variances in thegenerated downhole pressure (annular mud weight) caused by the relationship betweenpressure and temperature with depth. Increase mud weight only if absolutely sure of increase in pore pressure ( increase intemperature , shut in pressure , well instability , Kick etc.). Pore pressures and pit levels must be monitored carefully at all times due to the lowtolerance expected between pore pressure and fracture gradients. Avoid rapid trip/running casing/ pipe movement to minimise swab and surge pressures.

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Hydraulics calculations undertemperature/pressure should be used to plan for trips e.g. the requirement to breakcirculation after trips due to an increase in mud density in the upper hole sections due tothe cooling effects of the mud system. The mud in the riser and upper 9 7/8“ casing will be cooler, heavier and thicker than themud at the section TD after a trip out of the hole. These conditions will result in anincreased ECD during initial circulating operations once back on bottom which couldbreakdown the formation. To avoid this problem, staged circulation will be made whilerunning in the hole to heat up the mud and break the gel strengths of the mud. Induced lost circulation can be caused by:

• Surge pressures while running in the hole (BHA/small diameter gauge hole). • High initial pump pressures and ECD required to break circulation (progressive gel

strength of the cooler mud). We recommend the drill-pipe is rotated to break the gelsstrengths prior to starting circulation.

• Barite Sag. See Appendix for further discussion. •

" Higher annular mud density after a trip, caused by cooler mud and the weighted

slug that was pumped prior to the trip. OWR: The OWR should be maintained at ± 80/20 - 85/15. Hydraulic: The yield point should be maintained in the range 15 - 20 lbs/100 ft2 in this

interval combined with minimum PV’s and gels in order to optimise hydraulics forminimum ECD’s/surge/swab pressures. The optimisation of rheology will be critically important through this interval to minimisesupercharging. A minimum circulating rate of 750 l/min is recommended to maintain adequate holecleaning.

HP/HT Filtrate: Maintain the HPHT below 3.0 cc @ 190ºC by the use of DURATONE

HT, and EZ MUL 2F Differentially stuck pipe: It will be beneficial to treat the mud with 2 - 3 kg/m³ of CMO

568, oil mud lubricant. Recent research indicates that the force required to freedifferentially stuck pipe, is substantially reduced when the filter cake containsBARACARB bridging material and CMO 568.

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H2S: Maintain excess Lime > 2 - 3 kg/m³, inorder to offset any H2S intrusion into the mud system.

Solids control: Run the shale shakers utilising the finest mesh screen possible. Shale shakers have to be attended to at all times, and screens changed as circumstancesdictate to keep the optimum screen size on the shakers. It is also suggested that both oblong, square and pyramidal screens be available on the rigsite and various combinations are tried for optimum performance. The base fluid washgun should be available to clean the screens.

Synthetic Oil on Cuttings: As in the previous section the Mud engineers performs theSOC on a composite sample every 300 metres or daily, whichever is the sooner. The mudengineer also collect all statutory samples while using synthetic oil base mud.

Barite sagging: SUSPENTONE can be added to the mud system at 4 - 6kg/m³ in order to

protect against Barite settling in the event of a large condensate/oil influx. Cement job: The mud should be treated with 2 kg/m³ DRILTREAT and EZ MUL 2F prior

to cementing to minimise the effects of possible spacer contamination.

FRANKLIN 29/5b-F3 Hydraulics analysis 8½" hole

m RT º lpm bars m/min m/min sg ºC sg ºC ºC ºC cPo lbs/100ft² lbs/100ft² EMW EMW EMW EMW EMW EMW

28/11/1998 5161 8 3 x 24 10 2.15 40 2.15 50 160 55 15 12 Hidra

29/11/1998 5161

30/11/1998 5174 5091 1085 90 199 9 6 x 10 11 71 45 2.15 37 2.15 43 60 23 13 Rodby/Sola

01/12/1998 5249 5166 1125 90 199 9 6 x 10 11 74 47 2.15 46 2.15 51 57 21 15 Valhall/Heather

02/12/1998 5343 5259 1120 90 193 9 6 x 10 11 74 47 2.15 47 2.15 54 59 26 19 Franklin 'C'/'B'

03/12/1998 5425 5342 1110 91 193 9 6 x 10 11 73 46 2.15 47 2.15 51 65 27 16 Franklin 'A'

04/12/1998 5595 5511 1110 90 201 9 6 x 10 11 73 46 2.15 46 2.15 51 60 23 16 Pentland

04/12/1998 5623 5539 1120 115 205 9 6 x 10 11 74 47 2.15 46 2.15 57 26 15

05/12/1998 5654 5571 1124 130 197 9 6 x10 11 74 47 2.15 46 2.15 51 56 22 15

06/12/1998 5709 5626 1124 124 199 9 6 x 10 11 74 47 2.15 47 2.15 50 51 17 14

07/12/1998 5757 5674 1130 130 175 9 6 x 10 11 74 47 2.15 47 2.15 52 52 22 15

08/12/1998 5807 5721 1100 130 200 9 6 x 10 11 72 46 2.15 40 2.15 53 51 21 14

09/12/1998 5807 5721 1100 15 200 9 6 x 10 11 72 46 2.15 40 2.15 53 51 21 14

10/12/1998 5807 5721 9 6 x 10 11 2.15 51 21 14

11/12/1998 5807 5721 2.15 51 21 14

12/12/1998 5807 5721 10 6 x 10 12 2.15 51 21 14

13/12/1998 5807 5721 1100 15 200 10 6 x 10 12 72 46 2.15 43 2.15 52 69 21 15

14/12/1998 5807 5721 10 6 x 10 12 2.15 69 21 15

15/12/1998 5807 5721 2.15 69 21 15

16/12/1998

17/12/1998

18/12/1998

19/12/1998

20/12/1998

21/12/1998

22/12/1998

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5.5 EXPERIENCE

The attached table is a recap of the main lessons learnt .

7

HP / HT SectionDRILLING FLUIDS RECOMMENDATIONS

8½” Drilling section


• Gas level shows ! All densities must be reported and corrected at 50ºC. • Back ground gas • Well Flowing ! Anticipated any degradation of mud for an extended static

period. DENSITY • Flow Check

instable Solution: over-treated the mud before the specific operations

“ Key Factor “

IT ISIMPORTANT TO

• Settling of Barite

RECOGNISETHAT MUDWEIGHT CANVARYSIGNIFICANTLYWITHTEMPERATURE

• Increasing of Solids

Content

! Start the section with 2.15 SG with Low rheology! Addition of Premix Weighted at 1.85 / 1.95 SG is recommeded

(Premix)! see Baroid practices! Keep LGS < 150 g/litre! Calibration of Pressurised mud balance with ZnBr2 solution! Pore Pressure on Fulmar Reservoir results : [ G4 i,e ]

Franklin “ C “ - 2.10 EMW at 5357 m TVD MDT ➝ Franklin “ B “ - 2.06 EMW at 5489 m TVD

Franklin “ A “ - 2.04 EMW at 5569 m TVD REMINDER ANY INCREASING OF DENSITY MUST BE EVALUATED • Plastic Viscosity (

PV )! A tight control of the PV is essential

Range : PV = 45 to 60 @ 2.17 Sg. ➝ Suspentone / Base oil / RM 63 may be used to increase the end

Rheology • YV Fluctuation

High Temperature ! Keep Yv at 15/20 under Static/Dynamic Temperatureconditions

• Gellation ! No progressive gels have been reported. Flat gels : 29 / 31 / 38 (Gels 0 / 10 / 30 min)

! Bottom up samples must be compared to regular mud . • Degradation at

Bottom up after atrip (i.e.)

! Static ageing must be used to predict mud behaviour when the mud is to be static for an extended period.

“RHEOLOGY”

• Low shearrheologicalproperties

• Yield Stress

! The ratio of quality organophilic clay to rheology modified is critical -

! Addition of SUSPENTONE as soon as barite sag start to be detected .( 3 to 5 kgs/m³ )

! Experience :" see Baroid recommendations Maintained with RM 63 - YS = 5 - 8 lb/100 sqft²

8

PARAMETERS

INDICATORS

RECOMMENDATIONS / FIELD RESULTS -


• API Filtrate• Change in HPHT

filtrate values after:Bottom up

• Hot rolling• Cake quality• “Barite Plug”

! Should be all oil throughout. In the lower sections tightcontrol across the sands may be required, especially if there issignificant overbalance.

! HP/HT Filtrate will be checked at 175º C top section , then

Filtrate should always be at the maximum BHST (200 ºC) atTD.

HP / HT Filtrate

< 3 cc at 190 °C ! Recommended treatment:

>EZMUL 2F + Invermul 2F 10 kgs/ m³ >Duratone HT 5 kg/m³ >Lime 5 kgs/m³ >Baracarb 50 10 kgs/m³ > Baracarb 150 5 kgs/m³

! Prior to tripping for a long extended period, spot an “over

REMINDER -treated” mud pill in front of reservoir: “Low Fluid LossPill Practice ”

• A “Mud core” has

been recoveredwhilst the first core

➝ Specifications: >Ezmul2F + Invermul 2F 15 kgs/ m³ >Duratone HT 10 kg/m³ >Baracarb 50 20 kgs/m³ > Baracarb 150 10 kgs/m³

REMINDER LIME EXCESS

• H2S• CO2

! Be aware that “Hydrogen Sulphide” has been encountered inCentral Graben wells.

! In SBM system maintain lime in system at 3 to 5 kgs/m3.! H2S procedures have to be initiated before this section! In SBM mud the increased reaction of lime with surfactants

greatly increases with temperature and reductions in mud alkalinity are common.

ELECTRICALSTABILITY

• E.S.

➝ Range 1100.volt > ES > 700 volt Good behaviour of mud system.

FLASH POINT! 90º C

(BASE OIL)

• • High temperature at

Flow line •

➝ ➝ Usually bottom hole section circulation’s rates are too low to cause a problem in 8½" diameter . At TD ➝ Temp in = 38º C with Flow rate = 900m l/mn Temp out = 42ºC.➝ ➝ A check of flash point must be done weekly in town.

TEMPERATURE

• Max Temperature

REMINDER

➝ Temperature maximum recorded = 205 °C BHST

W.P.S. (WATERPHASESALINITY)

• Decreasing

➝ ➝ This appears to only be important on the upper sections where

clay instability can occur at chloride levels above 180 gr/l. ➝ Keep WPS > 190 gr/l

9

PARAMETERS

INDICATORS



WELL-BORESTABILITY

• Shale “Cavings”• Sticking• Core Damage• Calliper• Losses in transition

zone

➝ In micro fractured shales, use a very low fluid loss mud. ( HPHT < 3 mls ) and add fracture sealing agent. ➝ Addition of Bridging agent is recommended > Baracarb 50 10 kgs / m³ > Baracarb 150 5 kgs / m³

Before drilling the pay zone > One arm caliper has been recorded on this section, giving a hole

in gauge. ( 8.7” average )

REMINDER ! An oriented 4-arm calliper is recommended EVAPORATION

• O.W.R. increasing(loss water phase)

• Salinity ↑• Increased gels

• Add water: Increased filtrate and surface evaporation reducesthe

total water of the mud and, if not replaced, will in effect,“dehydrate” the system.

Warning Any addition of water must be checked by ageing “pilot test” due

to the contamination effect (Rheology affected). REMINDER An increasing of OWR has been reported without any explanation -

But no impact on the behaviour of mud and Operations • Mud Behaviour

• ThermalDegradation

Typical Composition : Drilling Fluids @ 2.15 SG.

CHEMICAL FONCTION TOPSECTION

ENDSECTION

XP 07 Base oil 470 litres 470 litres

WaterCa Cl2

120 litres30 g/ l

105 litres20.83 g/l

CHEMICALSCONCENTRATION

E2 MUL 2F PrimaryEmulsifier

42 g/l 76.2g /l

BARITE Weighting agent 1460 g/l 1268 g /l

Geltone IV viscosifier 3.14 g/l 4.85 g/l/

Invermul 2FDuratone HT

Second.EmulsifierFluid Loss

control

0 g/l27.67 g/l

9.13 g/l38.52 g/l

LimeRM 63 Rheology

modifier

18 g/l0.86 g/l

7.8 g/l2.28 g/l

Suspentone Suspension agent 3.42 g/l 6.28 g/l

Baracarb 150Baracarb 50

Bridgingchemical

8 g/l27 g/l

8 g/l27 g/l

10


“ Low Fluid LossPill over-treated “

• Anticipatedtreatment for SpecificOperations : Logging/Coring/tripping

Spot pill mud in the Open Hole , made of Active mud over -treated for fluid loss reduction .Displace in pump out mode . Formulation : >EZMUL 2F 5 litres/m³ >Invermul 2F 5 litres / m³ >Duratone HT 5 kg/m³ >Lime 10 kgs/m³ >Baracarb 50 5kgs/m³ > Baracarb 150 5 kgs/m³

REMINDER Products concentration should be reported daily on the current

mud.

TRANSITIONZONE

KIMMERIDGE

CLAY

• Kick and Lossessimultaneously

• Flow check

inappropriate • B.G.G. Levels • Free Emission of

gas in SBM

REMINDER

Action: > Anticipated risk of losses by adding Bridging agent in the mud(Baracarb , Duratone HT…) > Start the section with 2.15 SG or less. See reports ( Well Instability Report ) > Reinforce Flow check procedure before coring point. > A well stabilisation must be recovered almost instantaneouslyafter the flow check (see Downhole measurements - ThermalEffect)

! Spot Hi Dens pill must be considered for the tripping. Volume = 20 / 25 m³ - SG = 2.30 ; PV =105 ; YV = 40 @ 50°C Note : Increase of viscosity will come only from barite addition ,otherwise heavy treatment will be required to restore the mud.

Results: Some Seepage losses were identified whilst this section with 2.17 SG , giving a measured ( PWD ) Equivalent Static Density of 2.18SG .

> Good behaviour of mud during investigation > Observe free gas at surface after long Flow check .. REMINDER For further wells it is believed that the use of a slightly lower mud

weight to drill through the Jurassic Kimmeridge shales shouldavoid lost time.( in decreasing the chance of supercharging theformation )

REFERENCE ➾ 22/30C-c10 “Wellbore pressure instability” ➾ HP/HT Transition zone analysis

FANN 70 ATDOWNHOLECONDITIONS

• Behaviour of Mudunder HP/HT

• Hydrauliccalculations

• Fann 70 tests must be run on the mud on a regular basiswhile drilling in the HPHT section.

“Look ahead” rheologies and gels to be run and the reaction of thecurrent mud to anticipated temperatures.

• Established a matrix P, T, depth -• No Fann 70 onboard

REMINDER • Fann 70 twice per week / normal operations

11

PARAMETERS

INDICATORS



P.S.D.

• To minimise LGS.

• Screen shakers optimisation , LGS content must be kept to aminimum < 150 g/litre .

FORMATION

DAMAGE• Downhole Pressure

measurements(supercharging)

• See MDT measurements ( No significant Supercharging ) 27 pressures ( good test : 15, seal failure : 3, tight 4, supercharged : 5 )

QA/QC

• Cake

• No major problems were reported

• “Formation damage” may arise in low permeabilityreservoirs with emulsion blocks or changes in wettability. Thiscan be avoided by using a very High oil / water ration formulation.

DIFFERENTIAL

STICKING• During Connection

or Coring• See Contingency Procedure - ( ZnBr2 formulation).

LOGISTIC • Stocks and Volume • Onsite keep 300m3 of mud to anticipate any risks in the

transition zone.• Keep LCM safety stock as per programme.

POLLUTION

ENVIRONMENT• Oil on Cuttings

Daily ReportedOOC < 10%

• The issue of the efficiency of the solids control equipmentand

the allocation of mud losses on site needs to be clearlyidentified

and documented:- The balance of the mud lost is a combination of other factors which

include: • losses associated with the operation of other down stream

solids removal equipment - e.g. centrifuges , mud cleaners• pit losses• tripping losses on the drill floor• interface losses displacing mud into the hole• evaporation losses• leaks from pits and pumps• whole mud losses over the shakers• header box spills• losses while reaming• losses while circulating and conditioning• losses while drilling cement• losses around the moon-pool• losses around the drill floor

Results:

OOC ➾ 11,36% - Base oil discharged ➾ 57,4 Tons

Target 10% 35 Tons

Need Improvement for further wells with the new Regulations

12

PARAMETERS

INDICATORS



WELL SITEPROCEDURES

• Hot Rolling• Ageing Tests• Mud Weight

• Hot rolling ovens, bomb and HPHT filtration cells should be used to optimise drilling fluids formulations.• Feedback if problems develop on the rig.• See Mud calibration check list - (Rig crew & derrickman )

REMINDER • For some treatments 2 - 3 circulation’s may be needed before

the effects are seen

LinerCEMENTING

Mud Conditioning

See 7” Liner Cementing recommendations

HYDRAULICS

REMINDER THE FOLLOWING GUIDELINES , BASED ON EXPERIMENTS , MUST RELATED TO THE MUD

PROPERTIES AT THE TIME OF THE TESTS .

• ESD • Influx of formationfluids

For 2.17 SG @ 50º with PV = 44 and YP = 12

• L.O.T. • ESD ➾ 2.19 (Expression of the static bottom hole pressure) with PV=44 , YV = 12

• ECD • Seepage Losses • SPP • ECD ➾ 2.25 (@ 1000 l/mn) and PV=56 ; YV=20 • Differential

sticking and 2.26 (with 60 RPM)

2.27 (with 120 RPM)

• Mud Compressibility Heavy mud ➾ 4.1 litre /100 bar / m3 or 2,9 litre / 1000 psi / m3

• Over Pressured to break Gels: 110 psi after 50 hours without Circulation

REMINDER ECD values are very dependant of the mud rheology .

PRESSURETRANSMISSION

• Pressure Transmission: @ around 80% of the pressure increment is transmitted nearlyinstantaneously. @ almost 100% of the pressure increment is transmitted after 30minutes.

13

PARAMETERS

INDICATORS



TRIPPING

SPEED • Swab & Surge - Tripping Speed:

• Main swab effects observed are:

✓ ESD variations are directly related to the tripping speed ✓ ESD variations are instantaneous ✓ ESD drop-off is constant during the one-stand trip. ✓ With a “low” tripping speed of 4 minutes per stand, the

observed drop-off in ESD is 2 points (0.02 SG) or almost 10 bars

✓ With a “very low” tripping speed of 7 minutes per stand, the observed drop-off in ESD is 1.5 points (0.015 SG) or almost 7 bars

✓ With a “High” tripping speed of 2 minutes per stand, the

observed drop-off in ESD is 3 points (0.03 SG) or almost 15bars

• Flow Check Flow Check & Mud Shrinkage • Several flow checks have been done during the tests with

some of them on the trip tank. • Flow checks when monitoring pits volume:

✓ The driller is no longer able to see any pit variations after 30 minutes (his pit volume indicator gives a constant value after 30 minutes)

✓ But detailed analysis of recorded data shows that pit volumes reach a steady state only after almost 120 minutes (2 hours)

✓ After a flow check, the normal procedure is to re-create the

previous well situation (same flowrate, same RPM) in order to confirm volume variations

✓ This operation takes around 20 minutes ✓ Volume variations include: flow line and lines volume

(instantaneous) + mud pressure drop-off of the mud in the well • Flow check when monitoring the trip tank volume: ✓ Detailed analysis of recorded data shows that trip tank volume

reach a steady state very quickly (after 10 minutes) ✓ These tests, performed in cased hole, are not showing any mud

thermal expansion (of the mud volume in the well)

14

PARAMETERS

INDICATORS



• SPP PREDICTION ✓ ECDELF is a new hydraulic software developed by the Elf

Exploration Production Fluids Group “ECDELF” • ESD

✓ Tests, validation and “operational improvements” will becompleted by the end of 1997.

• Validation of the results given by the present version of

ECDELF (1.01 test): ✓ ECD : OK without rotation ( within a range of flowrate )

(the present version of the software does not take into accountthe effect of rotation on the annulus pressure losses)

REMINDER The programme need still developments : today value are corrected in a 1000 - 1200 litre/min range , at low flowrate the ECD predictions are too high and at higher flow rate the ECD prediction are too low .

REMINDER ✓ ESD : seems to be slightly under-estimated

(the ESD calculated by ECDELF is always 1 point lower thanthe measured ESD). This will be improved with more accuratePVT equations for the XP07 base oil PWD measurements are still mandatory

✓ Stand Pipe Pressure : are slightly over-estimated (around 3 to 5 %)

SPP are strongly affected by the internal string pressure losses;flow regime inside the string is highly turbulent even at 1000LPM and calculations are based on empirical correlations (it isalways the case with turbulent flow); moreover equivalentshear rates seen by the mud are much more important than the600 RPM measured by classic rheometer.

And it is always difficult to know the exact drill string

geometry (especially the string ID and the tool-joints ID). However 5 % is a reasonable accuracy in on-going operations.

Hereafter is proposed a trick to improve SPP prediction in orderto better match with real-time measurements.

REFERENCE: David BERTIN

REPORT

** Downhole Pressure & Temperature Measurements on HP/HTwell.

( 28 / 08 / 1997 ) • For a more efficient use of the present version of ECDELF(version 1.01 test):

REMINDER Do not forget that the current test version of ECDELF do nottake into account the effect of pipe rotation on the ECD; justadd to the results 0.01 SG per 60 RPM to get accurate ECDpredictions

15

PARAMETERS INDICATORS SHELL SHEARWATERRECOMMENDATIONS / FIELD RESULTS

COMPARISON TO ELGIN-FRANKLIN

Variation withtemperature

For the Shearwater project, the density was measured at a standardtemperature of 100ºF (37ºC). The standard temperature is definedas the surface temperature, at which the surface mud weight will beexactly the equivalent downhole mud weight, at the top of thereservoir under geothermal gradient.The same approach was made on Elgin-Franklin, but mud weightswere reported at 50ºC.

Overbalance onreservoir

A 200-psi (0.03sg) overbalance at the top reservoir is usually usedfor the design of the mud. However, 120-psi (0.015sg) overbalancewas used on one Shearwater well, with a mud weight of 2.26sg.The same 0.015sg overbalance was used on Elgin G8 well.

DENSITY

Balance calibration The balance was calibrated with caesium formate brine at a densityclose to that of the active mud system.Elgin/Franklin: 1.70sg calcium bromide brine was used on firstwells, then replaced by 2.10sg caesium formate brine.

Plastic Viscosity The plastic viscosity of the mud was optimised with the addition ofemulsifiers. As the concentration of emulsifier increases the PVdecreases until it reaches a plateau; optimum treatment is thenachieved. Undertreatment with emulsifiers is very detrimental andcan contribute towards barite sag.Emulsifiers were also used to optimise the rheology of the mud.XP-07 mud (E/F) promoted lower PV than Ultidrill mud(Shearwater) through lower cinematic viscosity of the base oil.

RHEOLOGY

Low shear rateviscosity

The 100-rpm reading was controlled between a maximum of 42 tominimise the ECD and a maximum of 35 to limit the barite sag.Same 100-rpm readings noted on Elgin-Franklin. Optimised lowshear rate viscosity, through yield stress.

Plastic Viscosity See aboveLow shear rateviscosity

See above

Synthetic Water Ratio The optimum SWR to minimise barite subsidence was determinedin the lab at 80/20. SWR at 75/25 or 85/15 was found detrimentalto the suspension of barite. The SWR was maintained in the rangefrom 79/21 to 83/17 in the HPHT sections. Maximum angle: 30degree.Elgin-Franklin: SWR from 78/22 to 90/10 were maintained with nobarite sag related problems, while drilling the HPHT sections. Thelower cinematic viscosity of the base fluid, allowed the use ofproper concentration of gelling agent to control the suspension ofbarite, without impairing the ECD’s. Maximum angle: 40 degree.

BARITE SAG

Wetting agent Slight overtreatment of wetting agents was recommended tomaintain the best wettability of the barite, to prevent its settlement.The same approach for the Emulsifier was used: the optimumconcentration of wetting agent was reached when the plasticviscosity was not further reduced.Elgin/Franklin: wetting agents were used to oil wet the baritewhilst adding weighting materials.

16

PARAMETERS

INDICATORS SHELL SHEARWATERRECOMMENDATIONS / FIELD RESULTS

COMPARISON TO ELGIN-FRANKLIN

HPHT fluid loss Maintained below 5 cc at BHST (182 to 193ºC).Maintained below 5 cc at 180ºC.

TEMP.STABILITY

Spotting HPHT Lowfluid loss pill

A high viscosity, low fluid loss pill was spotted in the open holebefore tripping to minimise the risk of sag and differentialsticking, and maximise the mud tolerance to contamination byreservoir fluid.This approach was imposed by SHELL, after ELF presented itssuccessful drilling of the first Elgin well. The HPHT fluid losspills are still in used in our fields, to prevent long termdegradation of mud under temperature and also, to prevent largedeposit of cake, prior to core the reservoirs.

HYDRAULICS ESD, ECD, Surgeand Swab

DOWELL software validated with Sperry-Sun PWD.ECDELF software validated with Sperry-Sun PWD.

Breaking circulationwhile running in thehole

To minimise the impact of barite sag, circulation while runningin the hole was only made at the 9 7/8” shoe.Elgin-Franklin: same approach.

Mud from 12 ¼” to 8½” section

Two separate mud systems, one for the 12 ¼” section and onefor the 8 ½” section were used. The HPHT mud werebackloaded and reconditioned in town before reuse.Elgin-Franklin: generally the mud from the 12 ¼” section werediluted and adjusted offshore for the drilling of the 8 ½” sectionwithout any impairment to the fluid nor the rig time.

OPERATIONAL PRACTICES

Continuity ofpersonnel

Shell: Dowell mud engineers assigned to the project.Elf: Baroid mud engineers assigned to the project were GrahamBell, Phil Leslie, Dan Blaylock, Roberto Cremascoli, Neil Rossand Ian Cameron.Same approach on both development to promote a continuousimprovement of the performances.

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5.6 7” ( or 7”x 4 1/2”) liner and cementing

A 7” liner (or a tapered 7”x 4 1/2” if Pentland drilled) liner will be run and cementedto the liner hanger. The goal of a tapered liner is to give us the maximum chance to obtain a goodisolation between the two reservoirs to prevent any future water production from thePentland by channelling behind the liner. Running the liner. Prior to run the liner, the gel strength and yield point must both

be reduced, the yield point + 15 lb/100ft², and the 10’ gel to < 23 to avoid excessivesurge pressures when running in. Pilot tests will be completed by the mud engineerto determine the optimum treatment levels. This can best be accomplished by additions of OMC 2.Care should be taken so asnot to over treat the system with OMC 2 that can cause barite sagging or settling.When running liner, consideration should be given to breaking circulation half wayin the hole, to reduce back pressure when breaking circulation on bottom prior tocementing. Swab and surge calculations should be run on the actual data of the time to optimisethe rheological properties and liner running speeds, to ensure they are well withinthe limits of fracture pressure.

Cementing job

The liner will be cemented with a gas tight slurry 2.30 SG. he slurry volume will be calculated according with the caliper volume + 20% andan excess corresponding at 100 metres of annulus volume (9 7/8” Csg x 5” DP).

Fluid design: ! Spacer : formulate spacer @ 2.25 SG.

Contractor Dowell Halliburton Spacer Mudpush WHT Spacer 500E+ Viscosifier D143 10 kgs/m³ 16 kgs/m³ Surfactant U66 - 47.6 l/m³ SEM7-50l/m3

Surfactant B064 – 47 l/m³ Pen5–20 l/m³ Bentonite D20 – 5 kgs N/A Stabiliser B78 – 8 litres N/A Fresh water 510 litres 538 litres Barite 1626 kgs 1622 kgs Defoamer as required as required

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Important : Spacer design becomes more challenging with Oil-base mud . The spacer must be cpmpatiblewith both the mud and cement while remaining stable at High Temperature . Oil waterEmulsions , such as the Dowell MUD Push XEO is not recommended . A water phase spacer with surfactant is recommended . Specific Lab. Tests : - Static Settling Test at BHCT . - Dynamic Settling test at BHCT - Compatibility with SBM and Slurry under temperature .

! Tail slurry: gas tight 2.30 SG. –! VOLUME = Caliper + 20% open hole + 100 metres aboveTOL ( 9 7/8” casing )

G cement Dowell HalliburtonDyckerhoff Lafarge

Silica 35 % Bwoc 35% BwocFluid loss D134 – 310 l/ton Halad600LE-90Stabiliser D135 – 31 l/T Silicalite 97L-100 l/TRetarder D161 – 173 l/T HR25L – 122.5l/ton

Drill Water 37 l/T Zero l/T

Dispersant B78 – 7.7l/T CFR3 – 0.5%Weighting agent Hematite 71% bwoc Micromax50% bwocStabiliser D153 – 0.2% bwoc Microbond Ht – 4%Retarder N/A SCR100L – 205 l/ton

Remarks:

1. All the formulations are indicative, they must be confirmed by laboratorytests performed with samples coming from the rig before the cement jobs.

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Density 2.30 SG.Yield +/- 1100 l/tThickening time > 8h00 + 3 Hours Batch mixingFluid loss < 30mlFree water < 0.0 %Compressive strength at BHCT >300bar 48 h

Additional Tests :

- Rheology at the BHCT using HPHT rheometer –- Settlement Test- Static Gel strength- Crush compressive strength- Sensitivity Tests :Temperature +/- 5°C and Retarder concentration +/- 5 % .

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- 5.7 EXPERIENCE :

Experience shows that advance planning and preparation are vital to thesuccessful completion of cementing operations .Prejob planning and careful consultation also save valuable time . Threeweeks or more are needed to ensure sufficient preparation for the cementingoperation , including a thorough examination of well conditions , spacerdesign , slurry qualification , operational mixing procedure .

The following pages examines current and evolving HPHT cementingpractices which was implemented during the drilling phase .

Example : 7 “Liner BAKER ( 42.5 # - 28% Cr.) Cement Job on 29/5b-F5

Objective:

The goal of the cement job is :- to seal the production liner covering the gas and condensate bearing sands of theFRANKLIN reservoir - isolate the GWC and the reservoir .

7” Liner String:

Top Liner: 5111 m MD ( 150 m overlap)9 7/8” Casing Shoe 5268 m MDLanding Collar: 5782 m MDFloat collar: 5879 m MD

Shoe Depth: 5910 m MDWell TD: 5915 m MDTop Franklin “ A “ Sands 5691 m MDPentland 5759 m MD

Radioactive markers and Joint markers:

To be positioned above C sands (One joint + 1 pip tag one joint above - 1 pip tag inthe Liner hanger)[ 8.55 m below top packer liner]Centralisation for this Liner should be as per following:

-2 Spiraglider Spiral Centralisers per joint over the 3 first joint (OD 8 1/4”)-1 Spiraglider Spiral Centraliser per joint over the float collar (OD 8 1/4”).-1 Rotating STT I SL Centraliser per Two joint over the Reservoir.

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-1 Rotating STT I SL Centraliser perThree joint from top Reservoir to 9 7/8”

- 1 Rotating STT I SL Centraliser per 2 joint from 9 7/8” to the top of the Liner.Type of centraliser; STT/I/SL model (OD 8.62”) - Installed over a stop collar (Mid

joint)Pre-job preparation:

1) Ensure all pits (to be used for the preparation of spacer and slurry mix water),cement supply to the Halliburton cement unit and cementing line to the rig floorare thoroughly cleaned out and flushed through with fresh water. Check cementbulk.

2) The 7” Liner will be drifted. It was dimensionally controlled to better assess theID of the joints which will be used for the displacement calculation.

Diameter: 5.788 “ or 16.98 L/metre3) Check wiper plug and dart for 5” DP - (Drifted + Rabbit the new 5” DP if

any)(Shear pins Wiper plug and Dart plug: Shearing value 1200 & 2200 psi -7

pins)

Good indication on F1: 122 bars with ENACO hanger.Good indication on F2: 126 bars with ENACO hangerGood indication on F3: 86 bars with BAKER hanger, unable to set hanger,

liner set on bottom of the hole.Good indication on F4: 155 bars with BAKER hanger.Tapered casing

7x5x4½”Good indication on F5: 95 bars with BAKER hanger

Mud film thickness inside DP and Liner:Vdp = 958 litresVliner = 233 litres

Total = 1191 litres => 70 metres, 7 joints

Preparation of Spacer

Spacer 1: Spacer 500E+ (High Temperature Spacer)The spacer to be used consists of 18 m³ of Spacer 500E+ (see Halliburtonformulation) weighted to 2.25 SG with a yield point of ± 40/50 (at 21 °C)

Mix 50 m³ of spacer to be able to fill the liner behind the cement - Lost suction on F2

Once the freshwater has been added to the pit, the chloride content of this watershould be checked, the result noted and a sample of this water retained. Take asample of spacer when complete, measure rheology at mix + at Halliburton labtemperature, note result and retain (compare with the formulation).

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Preparation of ADDITIVES:Addition of Fresh water, Halad 600LE, Silicalite-97L, Micromax will bemixed while RIH. This mix water can be kept 24 hours without harm to thecement job.

F1 - 9 hours to mix the slurry, SEE HALLIBURTON report for details.F2 - 7 hours to mix the slurry - Addition of micromax 10/15 min/ ton but still

very messy -Blockage of discharge line of 4” slurry followed by blockageof the 4” slurry suction line on the batch tank - Densitometer line blocked- Total downtime: 2 hours –

F3 – Mixing + recirculating slurry: 15 ½ hours. Slow addition of Micromax, ittook time to remove the bags from the containers.

F4 – 8 hours to mix the slurry – The mix water was started one hour before theliner tagged the bottom of the hole – The micromax took 4 hours to bemixed – the cement addition took 3 hours. The slurry was kept 2 ½ hourscirculating while pumping the spacers.

F5 – The micromax took 45 min hours to be mixed – The slurry took 90 min .

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Running procedure and Fluid pumping Sequence

Recommendations:- A circulation will be performed at the 9 7/8” casing shoe to establish parameters.

Circulate 1 bottom up at 750 L/min or less if losses are reported (gas level control,losses).

F1 @ 650 l/min SPP = 65 bars at 5118 mF2 @ 680 l/min SPP = 73 bars at 5002 mF3 @ 750 l/min SPP = 84 bars at 5126 mF4 @ 650 l/min SPP = 81bars at 5424 mF5 @ 750 l/min SPP = 80bars at 5240 m

- RIH and tag bottom - Pick up to liner setting depth according to liner operator.

On F5 : Washed down from 5367 m to 5913 m with 400 to 700 l/min & 55 to 90bars while working string through several tight spots -

- Break circulation slowly and check surface pumping pressure at previouslyestablished rates. Whilst running in the hole with 7” liner, select 1 high pressure mudpump and check seals, liners and swabs in case it is required during the cement job.

- At TD, take weight up / down. Tag TD + pull back +/- 2 metres –- #### Up / Down F5 : 248 / 212 tonsFluid pumping sequence:

1)- Circulation prior to the job should be, at a minimum, 1.5 times complete annularvolume.

The flow rate will be gradually increased while monitoring for losses to reach an ECD2.24 sg. at 700 lpm.

F5 at TD : Circ with 700 l/min – SPP = 84 bars .

Start the pumping slowly until the mud circulated from the bottom of the well haspassed the liner hanger to try to ensure no plugging of the (liner hanger x 7" casing)annulus with cuttings.If losses (> 3 m³ / hour), spot 10 m³ of LCM (BARACARB 50/150/600) 250 kg/m³.

2)- Set liner hanger (see BAKER procedure).

INCIDENT :During the circulation after setting the liner hanger , a leak was observed between the plugdropping head and the TIW valve directly below .The string below the connection fell ,breaking off the side entry sub thread complete with blanking cap as it travelled throughthe rotary table .[ see trip report ,and Baker report ] –Lost time : 5 h 00 .

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Mix and pump: Example on F5 well

1 - 50 m³ of low rheology ( PV= 66 , YV = 9 Gel 10 = 10 /15 ) mud at 2.15 SG.

2 - 18 .8 m³ of Spacer 500E+ at 2.25 SG ahead of cement slurry.

3 - Slurry, formulation as per attached Halliburton Fax.

The Volume required is as follows: volume to fill open hole annular volume + 30%excess on open hole + shoe track + 100 metres of 9 7/8” casing.

Estimated volume:Annulus volume: 8.1 m3Excess 30% or calliper volume: 2.4 m3Overlap150 m: 1.9 m³Shoe / FC: 2.4 m³Excess above top liner 100 m: 3.8 m³Total: 18.8 m³ at 2.3 SG (119 bbls)- SEECALLIPEROn F1: total slurry pumped -> 19.5 m³, top of cement at 4778 m, cement found 85metres higher than planned.On F2: total slurry pumped -> 20 m³, top of cement at 4740 m, cement found 4 metreshigherthanplanned.On F3: total slurry pumped -> 19.5 m³, top of cement at 4906 m, hard cement 85 mabove top of linerF4: total Slurry pumped -> 27 m³, top of cement at 5095 m , hard cement 74 m abovetop of liner.On F5: total Slurry pumped -> 18.8 m³, top of cement at 5013 m , hard cement 98 mabove top of liner.- No Freash water ( liquid phase coming from the additives )- Add Halad 600 LE- Add Silicalite 97 L- Add FDP-C533 and allow to hydrate for 30 min- Add SCR-100 L (liquid additive)- Add total Micromax (big bags & sacks) to the mixing water- Add ¼ of total Lafarge G + 35 % SSA- Add HR-25 L- Add remainder Lafarge G + 35% silica - Slurry weight should be 2.29 SG- Add Microbond HTWhen completed, take a sample of the slurry, measure the rheology & density andretain. Allow slurry to homogenise (+/- 30 min, with paddles and centrifuge pump)prior to pumping downhole .

4 - Release the pump down wiper dart.

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5 - Displace with (Halliburton unit) 12 m³ ofSpacer-500E+ at 2.25 SG behind cement slurry (to place the spacer inside the drill pipe abovethe running tool).

6 - Displace with (Halliburton Unit) with 2.15 SG mud at 700 litres/min until dart is circa 1 m³from latching into liner wiper plug and slow rate to 200 litres/min to pick up and shear outwiper plug. Increase rate to 300 litres/min to displace cement slurry in the liner, slowing tobump plug.

F2: Reduce to 300 l/min on the last 5 m³ to limit ECD @ 2.25 SG (see cimentelf)

Displacement to be calculated with 9 .06 l/m for S135DP & 8.00 l/m for G120 DP

ECD estimation before bump the plug: .26 EMW at TD (300 lit/min)Surface pressure before Bump: +/- 68 bars (300 lit/min)CIMENTELF

On F1: Surface pressure before Bump on the RIG: 50 bars (low flow rate )On F2: Surface pressure before Bump on the RIG : 55 bars ( low flow rate )On F3: Surface pressure before Bump on the RIG : 68 bars ( 430li/min )On F4: Surface pressure before Bump on the RIG : 66 bars ( 340lit/min )On F5: Surface pressure before Bump on the RIG : 67 bars ( 300lit/min )

Bump plug to 150 bars and then pressure test Liner to 220 bars

7 - After bumping plug, hold pressure (10 min Max) and check float equipment isholding.POOH 4/5 stands and circulation the long way until clean returns monitoring forlosses & gas .

F1: GAS MAXI after First bottom up 12.2 % - 20 min .F2: GAS MAXI after First bottom up 1 % - 28 m³ spacer contaminated.F3: No gas, reduced flow from 1500 to 1200 lit/min after 1 m³ loss. Recovered spacerreturnsF4: Recovered 16.8 m³ of spacer contaminated with 11.5 m³ mud.F5: Recovered 22 m³ of spacer contaminated .

Reciprocate and rotate (to avoid gelling effect) whilst circulating conventionally toevacuate spacer and excess cement at 1200 /1500 l/min (depending on pressure). Dumpcontaminated returns (in a dedicate pit, keep a sample of slurry if any) and increase flowrate to 1500 l/min, maintain this flow rate for one bottom up. Treat mud for suspension.

8 - Gas Migration potential during setting time:

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W.O.C for +/- 11 hours from start of pumping the slurry before POOH setting tool.Flow rate = 1400 l/min.Pressure = 170 bars.

9 - Timing: Estimated Actual

Mixing + Slurries Injection : 300 min 240 minDisplacement N° 1 : 100 min 150 minCirculation long way : 60 min 90 minSafety factor : 120 minTotal : 8 hours 40 min 8 hours

Notes: All samples of fluids should be 1 litre in size.Chloride content of Fresh water should be less than 1000 mg/litre.Record temperature of each fluid pumped in the well.

10 - Temperature Estimation:

Drilling 8 1/2” ( 1100 l/min)

BHST New APIBHCT

Hall.Enert.BHCT

EnertechBHCT

PWD BHCTbottom

RigFlow line

198°C 177°C 182 °C 182°C 172°Cforecast

53°C

Static temperature at top of cement: 175ºC

Bottom hole logging temperature on F5 : 193º3 C at T.after 58 h 50 min ;

Thickening Time:Tail Slurry: BHCT = 182 °C $$$$ 7 h 37 min + 3 hours surface mixing time

Tail Slurry: BHCT = 187 °C $ 5 h 58 min

Tail Slurry: BHCT = 177 °C $9 h 25 min

Compressive Strength at 175 °C$ 4277 Psi after 16 hours

11 - Compatibility test between mud / spacer:

12 - Retarder sensitivity tests (see attachment) :

Sensitivity to retarder concentrations: + / - 5 %: Thickening time .

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Note: the setting time will be checkedoffshore with a rig consistometer to forecast the time.

F1: Thickening time 9 hours 45 min on site at 16000 PSI and 182°CF2: Thickening time 7 hours 40 min on site instead of 7 hours 26 min at 16000

PSIand182°CF3: Excellent correlation on site versus laboratory.F4: Thickening time 8 hours 23 min on site instead of 8 hours 21 min at 15000 PSI and

182°CF5: Thickening time 6 hours 10 min on site instead of 7 hours 37 min at 15000 PSI and

182°C

** Slurry was kept 2 hours 30 min in the batch tank

EXPERIENCE

Difference in Cement Thickening Time between lab test and Offshore tests .

Advantages• If the Thickening time of the slurry is suitable the cement job can be performed in its entirety

without any risk of premature setting . To be more confident and especially with thecomplexity of the slurry recipe to check on site the T.Time by using a rig site consistometer. Few differences in the Thickening time were found between the lab tests onshore and thetest done offshore using the same chemicals and additives .

ExperienceTo date we have ran 11 Liners under Extreme conditions : Slurry density = 2.30 SG .

Well NameContractor

T.Time Lab. T.Time on site Depth Liner Length

HALLIBURTON BHST = 198°CBHCT = 182°C

29/5B - F1 07 h 18 min 09 h 45 min 5927 m 960 m29/5B – F2 07 h 40 min 07 h 26 min 5787 m 935 m29/5B – F3 07 h 48 min 07 h 26 min 5807 m 815 m29/5B – F4 08 h 21 min 08 h 23 min 6453 m 1182 m29/5B – F5 ** 07 h 37 min 06 h 10 min 5915 m 806 m29/4D - 4 07 h 16 min 07 h 34 min 6050 m 1025 mDOWELL BHST = 192°C

BHCT = 170°C22/30 C – G4 20 h 00 min 20 h 30 min 5884 m 854 m22/30 C – G5 09 h 02 min 08 h 13 min 5672 m 768 m22/30 C – G6 10 h 47 min 10 h 45 min 5928 m 704 m22/30 C – G7 11 h 26 min 08 h 25 min 5724 m 746 m22/30 C – G8 08 h 10 min 08 h 50 min 6147 m 800 m

Note:

** on F5 the slurry was kept 2 hours 30 min in the batch tank due to a pressure leak at the cementinghead .

1

HP / HT SectionCEMENTING RECOMMENDATIONS

7 ” Liner. Shoe depth @ +/- 6100 m MD - Top @ +/-5000 m MD.

PARAMETERS INDICATORS RECOMMENDATIONS RESULTS / RemedialActions

PRODUCTIONCOLUMN DESIGN

♦ Reservoir isolation

♦ Water productionprevention

• Liner lap cemented

• Shoe track cemented

• Good CBL

! Elgin: all drawdowntest (-570 bars) withstable flow checks.

! Franklin: hard cementat top of liner.

! CBL showing goodbonding in front offormations.

SLURRY WEIGHT

♦ Determination

♦ Adjustment

To help mud displacement with cement, slurry musthave a weight at least 5 points higher than the mud,and this weight must be compatible with theformation pressure to avoid any losses. In this section the mud weight is 2.15SG, so wegenerally use slurries at 2.30SG. Use Big-Bags and sacks of weighting agent(Hematite, Micromax…) to adjust the Final density.

! Good muddisplacement, and rareformation losses.

! NO MAJOR

PROBLEMS FORMIXING.

SLURRYTHICKENING

TIME

♦ T.T.Depends on theBottom Hole Circu-lation Temperatureand the pressure.

♦ BHCT estimated withseveral methods:- API table.- Enertech software.- Cemcade software.

♦ Sensitivity Tests:- Temperature- Concentration

♦ Safety:

These different methods give different results for thesame BHST (ex: API: 168°C, Enertech: 182°C,Cemcade: 170°C for BHST=198°C).• Check the Slurry Thickening Time at the highest

temperature found.• Control it at the other temperatures (including the

circulating temperature estimated at the top ofliner).

• Thickening time control on site with aConsistometer.

• Circulation with drill pipe above the cement tomaintain ECD (circulation time: based oncompressive strength at the top of liner) andavoid any gas influx.

• Have a right angle cement setting profile to avoidany influx during the cement transition period.

• Run tests with + / - 5% of retarder concentrationand +/- 5°C of temperature discrepancies.

• Adjust the TT to have the safety margin (+ 2hours) for the cement Job . The quantity ofretarder is significant so a special attention isnecessary when preparing the mixing water.

! On site thickeningtimes were in goodagreement with thetesting performed inthe lab.

! Slurry displacements

performed without pro-blems.

! Generally good CBL. ! Good response

COMPRESSIVESTRENGTH

Checked after 24 hours atthe temperatures given byEnertech software at thetop and the bottom ofliner.

Wait until the cement is set at the top of liner.

Compressive Strength:4500 psi after 13 hours atbottom conditions and2900 psi after 20 hours attop of liner conditions.

2

PARAMETERS

INDICATORS

RECOMMENDATIONS

RESULTS / Remedial

Actions

FILTRATION

FREE WATER

♦ Fluid loss control ♦ Free water control

• “Gas block” slurry design to have a tight Fluid

loss and avoid dehydration in front of reservoirs.

• Need zero free water to avoid gas migration orsettling

RELIABILITY Slurry homogeneity

• In order to have steady and reliable

characteristics, all the slurry will be prepared insurface (batch-tank) before being pumped.

• Quantity of water and additives must be carefullychecked.

• Use pressurised balance to check slurry weight.

Slurry on the site in goodagreement with lab-test.

SPACER

(Critical issue)

♦ Compatibility withSBM and Cement.

♦ Rheology under

HP/HT conditions( run Fann 70 )

• Laminar Flow Design • Emulsion design • Volume ahead /

behind

REMINDER

Rheology .Sensitivity test with blends at: 5 / 10 / 20 / 50 / 75 / 100 % Check Rheology under High Temperature to avoidany settling . ( @ BHCT ) Slim margin between Pore Pressure and Fract.Gradient - Laminar flow is recommended. Don’t Use “Base oil” for Spacer with compliantSurfactant – Pump spacer behind Slurry, which will be placedinside the drill pipe above running tool afterdisplacement. USE A WATER BASED SYSTEMTREATED WITH SURFACTANT.

! No channelling was

reported.! Good interface during

reverse circulation! No segregation of

solids versus liquidphase (oil & water).

! No problems during

disconnection ofsetting tool

SLURRY VOLUME • Excess + 30% calliper+ 100 metres in 9 7/8”

Increase the volume to get 100 metres above TOL +an excess of 30 % on Calliper

! Dowell: No tag of hardcement at the TOL.

! Halliburton: Tag hardcement for eachcementing job.

DISPLACEMENT

• Volume

• Flow rate

Used cementing unit for slurry displacement Used CIMENTELF software to calculate: - ECD and maximum flow rate acceptable during the

displacement. - TP and CDP factors (Cleaning and Laminar Displa-

cement Efficiency factors)

! Better accuracy ofdisplacement volume

! Losses during cementjobs were rare.

! Difficult to achieve aCDP > 5 (CDP>10 fora good displacement).

3

PARAMETERS

INDICATORS

RECOMMENDATIONS

RESULTS / Remedial

Actions

BATCH MIXING /ADDITIVES

PREPARATION

♦ Mixing Water

♦ Retarder HT ♦ Weighting Agent

(Hematite or Micro-max) in big-bags.

♦ Volume

♦ Mixing energy

♦ Efficiency / Yield

after ageing

Special care for Additives mixing – Follow Dowelland Halliburton Mixing procedure (and checkchloride in water before any mixing). Addition of HT RETARDER done ONCE LinerHanger is Set

Need RIG Modification to install a pipe from UpperDeck to the Batch Tank ( Minimum size = 10 /12”Diameter )

• Batch Tank Capacity = Minimum 150 BBLS. • Mix water should not be kept longer than +/- 8

hours. Mix water can be kept for 24 hours butthickening time will be reduced by 1 hour .

• Temperature of the slurry > 30°C

• Risk of evaporation of water during the recircu-lating of the slurry with an impact on the thicke-ning time.

• Thickening Time checked with Mix Water aged20 hours at room temperature

! Request 4 / 5 Hour to

mix all Big Bags

! Reached 2.30 SGwithout anyreadjustment.

DISPLACEMENT

VOLUMECALCULATION

♦ 7” casing size typical

ID 8.617” – 16.92lit/m.

♦ ID of DP volumes

♦ Compressibility

• Check Internal diameter with Micrometer

recordings This check is crucial to achieve agood displacement of the slurry.

• Use 9.06 l/metre for S135 DP & 8.00 l/metre forG120DP

• Mud compressibility not to be added to thetheoretical volume.Pumping DP volume + liner volume + mudcompressibility + ½ shoe track => Wet shoe

! Bump the plug : OK

! Plug shearing OK,typically 100 to 150bars.

! Test liner to 150 bars

CEMENTEVALUATION

• CBL/VDL Log

• Problem with CBL tool, risk of damagecentraliser in hole.

• Recommendation must be issued before each log

• Tool calibration needed before eachlogs.Free pipe for the 7” under wellconditions with Mud (SBM at 2.15 SG):DOWELL- 7” 42.7 # CBL ( free pipe with mud ) = +/- 61 mV .TT = 290 µ sec.- Fluid Compensator Factor : 0.466- Cement bond amplitude-Acoustic impedance

with a 2.30sg slurry weighted with Hematiteslurry is: 6.5 Mrayl

HALLIBURTON- 7” 42.7 # CBL ( free pipe with mud ) = +/- 61 mV .TT = 280 µ sec. - Cement bond amplitude - Acousticimpedance with a 2.30sg slurry weighted withmanganese oxide slurry is 6.6 x 106 kg/m² sec .

! CBL:Generally good resultsin open hole, badresults in over-lap,even when we drilledhard to very hardcement at the top of theliner.

! Shoe track:F3z Triassic welldeepening, the 150 mshoe track was drillout. The first 40 mwas cementedproperly, ROP = 10m/hr with WOB at 5tons. The 110 m belowwas a poor cement, 20to 40 m/hr with 2 to 5ton WOB.

4

PARAMETERS INDICATORS RECOMMENDATIONS - ACTIONS TAKEN

CEMENTING

PRACTICES

• Liner StringPreparation

• Fluid Design • MIXING

SEQUENCE • PUMPING

SEQUENCE

• Length of Overlap: 150 metres• Length of LC/Shoe: 150 to 200 metres

(mud film , dart failure , contamination)• Centralization: 2 per /J on 6 first J.

then 1 per / 2J Spiralglider ( OD 8 1/4” ) - STT/1/SL ( OD 8.62” )

• Mechanical Liner Hanger T I W or Baker• Rabbit DP 5” + ID measurement on 7” Liner • Spacer design : 2.25 SG

Laminar flow design , Compatibility testsrheology at BHCT Stability of spacer after adding surfactant .

• Thin Mud : 2.15 SG with PV= 45 / YV = 10 - +/-36 m³ pumped ahead spacer .

• Excess of slurry = 30 % on Calliper + 100 metresinside 9 7/8”without DP in hole

• Consistometer on the location• Chemicals checks according to the Lab. Test

(Reference number)• Flow meter with gauge to mix additives. • Batch Tank mixing.• Additives mixed during circulation at bottom

without retarder.• Addition of retarder once Liner Hanger set.• Mixing cement slurry to 1.90 SG with slurry chief

( temp.= 19°C ).• Addition of Hematite with Big Bags (5 min per

Bags), to 2.30 SG (temp. = 20 °C) – Norecirculating pump (only paddles used).

• Check rheology / SG / Volume (run consistometretest).

• Pump 36 m³ of thin mud (2.15 SG).• Pump 15 m³ of Spacer (2.25 SG).• Pump 18 m³ of Slurry (2.30 SG).• Pump 13 m³ of Spacer (2.25 SG) - Fill up liner +

150 m DP.• Pump SBM mud for Displacement

(2.15 SG). Check dart shearing / Bump plug at thetheoretical volume.

• Pressure Test to 150 bars (10 min).• POOH Slowly 4 Stands above TOL.• Direct Circulation at low flow-rate (Dumped

spacer / traces cement / spacer).• Circulation long way twice based on the

compressive strength at the top of liner.

5 5/8" OH / 4 ½ " liner 7 x 5 x 4 ½ " liner

Well 29/5b-F1 29/5b-F2 29/5b-F3 29/5b-F3z 29/5b-F4 29/5b-F5date 23/06/1998 15/09/1998 17/12/1998 01/05/2000 17/04/1999 24/09/1999

Top of cement m 4868 4742 4891 5553 5169 5009Casing shoe m 5926 5785 5806 6253 6452 5910Height m 1058 1043 915 700 1283 901BHST ºC 197 197 198 204 198 198BHCT ºC 182 182 182 195 182 182Type of slurryTheoritical slurry volume m³ 18.5 18.4 16.6 6.3 22.3 16.3Excess % 25 18 (caliper) 30 (caliper) 50 30 30Total slurry volume m³ 19.4 20 19.5 7.7 27 18.8Weight of cement (G+S) ton 28 26 26 13 36 24.3Slurry weight sg 2.30 2.30 2.30 2.30 2.30 2.30

Cement Lafarge G % 100 100 100 100 100 100Silica flour % 35 35 35 40 35 35Water type Fresh Fresh Fresh Fresh Fresh FreshAdditives 50% Micromax 50% Micromax 50% Micromax 60% Micromax 50% Micromax 50% Micromax

90 lit Halad-600 LE 90 lit Halad-600 LE 90 lit Halad-600 LE 130 lit Halad-600 LE 90 lit Halad-600 LE 90 lit Halad-600 LEl/ton 100 lit Silicalite-97 L 100 lit Silicalite-97 L 100 lit Silicalite-97 L 100 lit Silicalite-97 L 100 lit Silicalite-97 L 100 lit Silicalite-97 L

or 0.1% FDP-C533 0.2% FDP-C533 0.2% FDP-C533 0.2% FDP-C533 0.2% FDP-C533 0.2% FDP-C533% 4.2% SCR 100 210 lit SCR 100L 210 lit SCR 100L 75 lit SCR 500L 205 lit SCR 100L 205 lit SCR 100L

2.1% HR 25 105 lit HR 25L 105 lit HR 25L 90 lit HR 25L 122.5 lit HR 25L 122.5 lit HR 25L4% Microbond 4% Microbond 4% Microbond 1.4% Component R 4% Microbond 4% Microbond

20 lit/ton CFR-3LThickening time (70BC) hr:min 07:18 07:26 07:25 08:14 08:20 07:37Compressive strenght 12 hr PSI 4074 3024 3100 750 3200 4900Compressive strenght 24 hr PSI 4392 4600 4640 2700 3000 4600Flow pattern laminar laminar laminar laminar laminar laminarSpacer type Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+ Spacer 500E+

sg 2.25 2.25 2.25 2.15 2.25 2.25Plug type TIW ENACO-TIW BAKER BAKER BAKER BAKERDisplacement type dart and plug dart and plug dart and plug wiper plug not sheared dart and plug dart and plug

29/5b FRANKLIN - 8 ½" OPEN HOLE / 7" LINER CEMENTATION

HALLIBURTON TEMPERATURE SIMULATION

Enertech Software .

Enectech Simulation for 7” Liner

To determine BHCT for 7” Liner cementation the following parameters wereassumed:

1) As mud pits are enclosed air temp – 20°C and wind speed – 02) Slurry inlet temperature – 19°C3) Spacer inlet temperature – 20°C

BHCT °C Mud inletTemp.°C

Displacementrate m³/min

Slurry ratem³/min

BHCT Enertec

197197197197197

5050506040

0.60.30.30.30.3

0.60.30.60.60.6

178179179180178

Conclusion:If BHST is 197°C then max expected BHCT is 180°C.

API 1992: 176°C API 1990: 176°C

Tests will be performed at 182°C with additional Thickening Time tests at 172°C and192°C

TEMPERATURE PROFILE FOR 7" LINER

0

1000

2000

3000

4000

5000

6000

7000

0 50 100 150 200 250

TEMPERATURE degC

DE

PTH

m UndisturbedAnnulusDrill String

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8 1/2" Temperature Prediction - 29/5B-F1

0

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40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

4740 5153 5142 5153 5161 5167 5209 5247 5293 5419 5452 5544 5637 5663 5671 5671 5671 5723 5756 5765 5800 5840 5860 5900 5927 5927 5927Depth MD

Tem

pera

ture

in °C

Geol.BHST

Enert. BHST

BHCT predict.

PWD

Temp in °C

Temp out°C

Series7

Series8

Series9

Series10

after 56 hours after 72 hours

Horner plot186.7°C 187.8°C

190°C

Log

ging

195°C after 55 hours197°C Extrapolated

Log

ging

Enectech Simulation for 7” Liner – Well 29/4d-4

To determine BHCT for 7” Liner cementation the following parameters wereassumed:

1) As mud pits are enclosed air temp – 20°C and wind speed – 02) Slurry inlet temperature – 19°C3) Spacer inlet temperature – 20°C

BHCT °C Mud inletTemp.°C

Displacementrate m³/min

Slurry ratem³/min

BHCT Enertec

198198198198198

185185185

5050506040

405060

0.60.30.30.30.3

0.60.30.3

0.60.30.60.60.6

0.60.60.3

178179179180178

157165170

Conclusion:If BHST is 198°C then max expected BHCT is 180°C.

API 1992: 167°C

If BHST is 185°C then max expected BHCT is 170°C.

API 1992: 156°CTests will be performed at 182°C and 170°C.

Page 1

8 1/2" Temperature Prediction - 29 / 4 D -4

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5191 5256 5315 5375 5424 5471 5508 5551 5598 5606 5624 5658 5685 5788 5824 5863 5982 5987 5992 5997 6002 6007 6012 6017 6022 6041Depth MD

Tem

pera

ture

in °C

Geol.BHST

Enert. BHST

BHCT predict.

PWD

Temp in °C

Temp out°C

Series7

Series8

Series9

Series10

Cor

ing

Logging after 59 hours T =195°C

Log

ging

Cor

ing

Cor

ing

DOWELL SCHLUMBERGER TEMPERATURE SIMULATION

Cemcade Software .

-------Results of Simulation------------------- Temperature simulationAPI BHCT = 174 deg.CSimulated BHCT = 169 deg.C -Fluid N°:6 – Group:MU-Name:Thin Mud-----Simulated MaxHCT = 171 deg.C Mud Type: Oil (Fresh/Sea/Oil)CT at TOC = 163 deg.C Solids : 39%Static Temp. 08:00 24:00 Geo. Temp Volume Fraction: Oil : 50%

deg.C deg.C deg.C -----------------------------------------------------------Borttom Hole 184 192 195

op of cmt 163 167 169 Press <Do> to proceed------------------------------------------------------

Cumul Time---------Period------------Flow Rate-----------Inlet Temp----Volume Unit---hh:mn:ss hh:mn:ss l/min deg.C Hole volume

Mud Circulation ---------------------------------------------------------------------------------------03:00:00 03:00:00 400 47 0.388………… ………… ……. ……… …………………… ………… ……. ……… …………

Slurry/Spacer Circulation ---------------------------------------------------------------------------------------04:06:40 01:06:40 600 26.667 Thin Mud04:31:40 00:25:00 600 26.667 MUDPUSH XEO04:58:20 00:26:40 600 26.667 Tail slurry------------------------------------------------------------------------------------------------------------------------

Static period after placement: 24:00:00 hh:mn:ss

TEMPERATG4 Chart 4

Page 1

8 1/2" Temperature Prediction - 22/30 C-G4

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4740 5029 5118 5214 5332 5371 5412 5600 5657 5717 5740 5740Depth TVD

Tem

pera

ture

in °C Geol.BHST

Enert. BHSTBHCT predictionPWDTemp in °CTemp out°C

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6. 5 5/8” SECTION (G4 + F3.z triassic )

Interval: 6050 m (MD) 7” shoe to 6400 m(MD)

Max expected BHP: Pentland 2.10 SG EMW.Expected temperature: 195°C BHST at 5800m TVD BRT.

205°C BHST at 6130m TVD BRT.

6.1 Purpose:Drill (and core) 5 5/8” hole through remainder of the Middle Jurassic (Pentland formation).The shoe will be set 50 TVD above the prognosed Bottom Pentland formation.Requirement is to cover reservoir(s) and ensure a good isolation between Franklin Sandsand Pentland.

6.2 Drilling procedure:

Run in hole with 5 5/8 bit and tag the cement.Decrease the mud weight to 2.12 - Drill out the cement and 5 m in the formation.LOT: LOT expected 2.30 SG (limited to 2.40 SG EMW).Perform a cement squeeze at the 7” shoe if LOT is lower than 2.15 SG EMW.Drilling and coring to the TD.Run and cement at 4 1/2 liner.

6.3 Expected problems:• For the 8 ½” section .Control the mud-weight is however problematic, as a result of

fluctuations of ECD (Equivalent Circulation Density), ESD (Equivalent Static Density)and the main problems is the narrow drilling window which in this phase should belarger than thermal expansion of the mud.

• Swabbing• Loss/Gain problems• Same others potential problems than in the 8 ½” section.

6.4 Drilling fluids

This phase will be drilled with the mud from the previous section lightened to 2.12 SG.

6.4.1 Typical composition of mud (see 8 1/2 section)

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Weight : 2.12 SG PV :ALAP, typically 40-55 CPo YP : 15-20 lbs/100ft³ YS : 8 - 20 lbs/100ft³ Gels 0/10’/30’ : 8/25/35 Filtrate API : 0 cc Filtrate HP/HT : < 5 cc E.S. : > 600 V Cl-(Water Phase Salinity) : 225 g/l H/E : 80/20 - 85/15 Excess of Lime : > 1.5 to 2 g/l

6.4.3 Safety stocks

Bulk material:

Barite : 150 t Cement G + Silica Flour : 100 t

Material in sacks or drums:

BARACARB 50/150 : 3 t / 2 t Chemicals to mix 150 m3 of synthetic base mud

Mud / Synthetic Base Oil:

Kill mud 2.45 SG : 50 m³ Base Oil : 75 m³

Recommendations (see 8 1/2 section)

6.5 First Experience Gained on 22/30 C – G4 Well

5 5/8” Section: Drilled from 5,884 metres to 6,103 metres ( 219 metres )

Mud System: XP-O7 Synthetic Base Mud.

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SUMMARY OF MUD PROPERTIESProgrammed Range Properties

during coringProperties

after coringMud Weight SG 2.12 2.06 2.06Funnel Viscosity sec/ltr na 69 80Plastic Viscosity lbs/100 ft2 ALAP = 40 to 55 47-52 58-60Yield Point lbs/100 ft2 15 to 20 10-19 15-26Yield Stress lbs/100 ft2 8 to 20 5-7 5-7Gel Strengths lbs/100 ft2 8/25/35 8-24-30 11-26-33Filtrate API ml/30 min 0 0 0Filtrate HPHT @ 190 °C ml/30 min < 6.0 4.0Filtrate HPHT @200 °C ml/30 min na 3.8-4.0 3.0-4.0Electrical Stability volts > 600 >600 550-600Chlorides (WPS) g/l 225 145-190 146-195Base fluid/ Water (H/E) 80/20 to 85/15 80/20 to 84/16 80/20 to

83/17Excess of lime g/l > 15 2.8-13.7 2.0-11.5

SUMMARY OF MUD CONSUMPTIONDistance drilled, metres 219Initial mud volume at start of interval, m3 609.5Volume built including maintenance, m3 177.7Volume at end of section, m3 242.1Volume used on interval, m3

Volume left in hole (suspension mud)69.5

197.7Consumption, m3/m 0.317Dilution (consumption less hole vol.), m3/m 0.303

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Objectives

The objective of the section is to core and drill 5 5/8” hole through the remainder of the MiddleJurassic Pentland formation (which lies immediately under the Franklin sands). The goal is to takecores in the sandstone that is interbedded with siltstones and claystones for laboratory analysis.The total depth of the well is planned at fifty feet above the true vertical depth of the prognosedbottom of the Pentland formation. Depending on the results of the cores, the E-logs, etc. a decisionwill be made whether or not to run a liner for further tests of the formation. If a liner is run, it mustcover the reservoir or reservoirs and ensure good isolation between the Franklin sands and thePentland sands.

Discussion.

After the cementation of the 7” liner, the pipe was pulled above the calculated top of the cement andthe hole circulated with 2.17 SG mud. The circulation of the mud was to provide an equivalentcirculating density to the cement that was higher than the static pressure of the drilling fluid. Thepipe was pulled from the hole and an 8 1/2” bit run in the hole to drill the cement in the 9 5/8” casingto the top of the liner. The drilling assembly took weight at approximately 4,956 metres, washed to5,026 metres, and hard cement was drilled to the top of the liner at 5,035 metres. The weight of themud was maintained at 2.17 SG while drilling the cement by the addition of pre-mix.

Scrapers were included in the string when running the mill to clean out the polished bore receptacle.The mill was laid down and the ENACO isolation packer was run in the hole, set, and tests made asper programme. At this time forty seven cubic metres of pre-mix were prepared to reduce thedensity of the XP-O7 synthetic mud from 2.17 SG to 2.06 SG to drill the Pentland formation. Theprogramme specified a 2.12 SG drilling fluid to drill the formation, but the programme was revisedto the lower mud density. The pre-mix consisted of 10 m3 of XP-O7 Base fluid, Duratone HT at24.1 kg/m3, EZ MUL 2F at 48.5 kg/m3, INVERMUL 2F at 16.2 kg/m3, Lime at 10.6 kg/m3, RM-63at 4.0 kg/m3, and SUSPENTONE at 7.2 kg/m3. After diluting the active system with pre-mix,Baracarb ‘50’ and Baracarb ‘150’ was added to the system at 2.8 kg/m3 and 0.9 kg/m3 to restore theconcentrations of bridging material in the mud.

The concentrations of the emulsifiers EZ MUL 2F and INVERMUL 2F were increased to counteractthe contamination of the mud by the spacer incorporated into the system during the trip into the liner.(Note: The contamination of the XP-O7 synthetic based mud by agents in the spacer meant that regularadditions of GELTONE IV, SUSPENTONE, and RM-63 had to be made for rheology/suspension.)The 5 5/8” bit was run to 5,427 metres and washed to 5,690 metres, the plug and collar were drilled andcement drilled to 5,871 metres where the integrity of the liner was checked. The shoe was drilled,formation drilled from 5,884 metres to 5,890 metres and a formation integrity test (FIT) performed.The FIT yielded a 2.35 SG mud weight equivalent that was more than adequate for the expectedformation pressures in the Pentland formation. One hundred seventy five cubic meters of reserve mudwas diluted from 2.17 SG to 2.06 SG. Calcium chloride, Duratone HT, EZ MUL 2F, INVERMUL 2F,and Lime were added to the dilution to

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maintain the concentrations of Calcium chloride at 39.0 kg/m3, Duratone HT at 69.0 kg/m3, EZ MUL2F at 60.0 kg/m3, INVERMUL 2F at 25.0 kg/m3, and Lime at 92.0 kg/m3.

Coring.

At 5,890 metres the core barrel was run into the hole to cut core #6. The core jammed at 5,902 metresafter cutting twelve metres of core. The coring assembly was pulled at this depth. Recovered 10.75metres of core.

Core #7 was cut from 5, 902 metres to 5,928 metres. Recovered 13.84 metres of core.

Core #8 cut from 5,928 metres to 5,944 metres before the core jammed. XP-O7 was added to controlthe density at 2.06 SG and EZ MUL 2F added to increase the electrical stability from 503 volts to theprogrammed six hundred volts or more. The decrease in electrical stability, increase in waterpercentage, increase in plastic viscosity, etc. was caused by rain water getting into the system. Thewater was incorporated into the mud because the 3 1/2” pipe was pulled “wet” and in the absence of afunctional mud bucket for this size of pipe it was necessary to take the run off into the drains from theentire surface area of the drill floor instead of the normal area of the bell nipple during a heavy rainshower. Recovered 3.57 metres of core.

Cut core #9 from 5,944 metres to 5,950 metres. While circulating bottoms up, two drums of RM-63and approximately 0.9 kg/m3 of SUSPENTONE was added for maintenance of the system. Theaddition of rheology modifier and suspension agent was made because the bottom’s up weights aftercores were consistently 0.04 SG higher than the 2.06 SG of the active mud. There was no indication ofsag because the mud weight did not drop below 2.06 SG when circulating. Recovered 3.5 metres ofcore.

Core #10 was cut from 5,950 metres to 5,965 metres. Before starting to core, 10 m3 of high viscositymud (159 seconds/litre) was pumped ahead of dropping the ball. The purpose of the high viscosity mudwas to try to fill the core barrel with thick mud to preclude the possibility of barite from settling out ontop of the core. Before pulling out with core #10, twenty cubic meters of low filtrate mud (1.8 cc/30minutes at 200º Celsius) was spotted on bottom. The purpose of the low filtrate mud was to reducethe possibility of filter cake build up in the open hole. Recovered 15 metres of core.

When the core was removed from the well, the bottom portion of the corehead was found to be twistedoff. A taper tap (spear) was used to try to engage the fish. During circulation of bottoms up afterfishing, eight drums of EZ MUL 2F and six drums of INVERMUL 2F were added to the system. Theemulsifiers were added because the well would be static during intermediate logging if the fish was notrecovered. The bottom of the corehead was not retrieved and two E-log suites were run problem free.The Schlumberger wireline logs indicated good gauge hole and a bottom hole temperature of 193ºCelsius was recorded.

Milling operations.

A mill was run in the hole to mill the fish. The hole was conditioned for a possible cement plug andside-track operation with 3.44 kg/m3 Lime, 5.24 kg/m3 EZ MUL 2F, 2.62 kg/m3 INVERMUL 2F. Thefirst mill run was substantially worn out when it was pulled. A quantity of cutters and identifiablecorehead parts were recovered in the junk basket on the first run. A second mill was run to mill on any

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remaining junk. Only minor wear was recorded on the millwith little recovery in the junk basket. Drilling operations were resumed after the second run with aPDC bit.

Mud weight.

The original programme specified 2.12 SG density for the drilling fluid in this interval. The mudweight was revised to 2.06 SG based.

Evaporation / mud cooler.

The mud cooler was not required because of the low flowline temperatures. The maximum flowlinetemperature recorded was 47º Celsius. The temperatures are low because of two factors. Firstly, thelow circulation rates mean that a small volume is being circulated through the area where the highbottom hole temperatures are extant. Secondly, the cooling effect of the mud passing through the riserwhich is in contact with 92 metres of cold sea water acting as a heat sink.

Alkalinity.

As in the previous interval, the constant addition of lime was required to maintain the alkalinity of thesystem. Levels of treatment were high and resulted in an increase to 58.32 kg/m3 of lime added overthe section. To maintain the alkalinity, treatments while coring/drilling of 3.0 to 5.0 kg/m3 wererequired. Even these additions did not substantially improve the recorded alkalinity. Low levels ofshear and long circulation times tend to make mud treatments less effective.

Sag.

Sag of barite was not detected in this interval of the well. A minimum of five kg/m3 of SUSPENTONEwas maintained in the system at all times to help preclude the possibility of sag.

When circulating bottoms up the mud weights from inside the cased hole were constant. The mud fromthe open hole section was heavier - typically 0.04 to 0.06 SG above the original mud weight. Thischange in mud weight was attributed to filtration to the hole. Given the amount of barite in the systemthe amount of filtrate that would have to be lost is very small, a loss of 2% would account for a changein the weight from 2.06 to 2.12 SG. Based on the volumes of heavy mud returned a filtrate loss of 1.0m3 would account for the increase in the returning mud weights from the open hole.

The 14 - 15 m3 of open hole volume was spread over about 50 m3 by the time it had travelled the 6kilometres to surface. During the returns from the cased hole the mud weight was constant. The onlyvariation being the change in weight with increasing temperature - at the reference temperature theweight was constant. The only change in the weight was from the open hole section and were in theranges described above. The increase in weight did not appear to be time dependent as similarincreases in the mud weight were seen after a short trip or after a trip following 6 days of no circulationduring the logging program. This would indicate a high degree of stability in the mud system at theelevated temperatures recorded on this well. The highest bottom hole temperature recorded during thefinal phase of the logging programme was 203 degrees Centigrade (401 degrees Fahrenheit)

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Low Gravity Solids.

The profile of the particle size distribution showed that low gravity solids were not a problem in thisinterval.

Geology.

Predicted Top Actual TopFORMATION TVD RTKB

mTVD RTKB

mTVD RTKB

mTVD RTKB

mMiddle Jurassic: Pentland Formation 5,923 5,776 5,842 5,700Total depth 6,323 6,176 6,103 5,960

Formation related problems.

No mud related problems were experienced while using Baroid’s XP-O7 mud system in this interval.The presence of water sensitive formations does not seem to be a problem because the formation waspredominately sandstone with stringers of siltstone and claystone and coal. The siltstone andclaystone stringers were adequately stabilised by the mud.

Liner.

No liner was run due to the absence of commercial hydrocarbons in the Pentland formation at thislocation. Following the logging programme the open hole section was plugged and abandoned. ThePentland formation was cemented up.

Solids control.

The primary solids control are the two BRANDT and five SWECO shakers. The BRANDT’s werefitted with 10 mesh screens on the top deck and by 30 mesh screens on the bottom. Due to the smallsize of cuttings when coring, virtually no cuttings were removed by the BRANDT shakers. Three ofthe SWECO shakers were initially fitted with 185x185x120 mesh screens, and the remaining twoSWECO shakers were fitted with 150x150x120 mesh screens. At the first opportunity after the mudsheared and heated up, two of the five SWECO shakers were shut down and kept on standby. Of theremaining three shakers, finer screens were put on shaker number four and number five. The set of185x185x150 mesh screens on shaker four was replaced by 250x250x185 mesh screens. The set of150x150x120 mesh screens on shaker five was replaced by 250x250x185 mesh screens.

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The Santa Fe ALFA LAVAL centrifuge was removed fromthe Galaxy I because it could not process the 2.17 SG XP-O7 from the 8 1/2” hole section to reduce itto 2.06 SG. The plan is for the centrifuge to be serviced before being returned for the next well.

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Recommendations:

1. TYPE OF MUD.

Type Used RecommendedXP-O7 - synthetic based mud XP-O7 - synthetic based mud

2. DENSITY.

An initial density of 2.06 SG provided sufficient over balance to the formation pressureinitially. There were no centrifuges to run when required in order to control the mud weight sothat dilution was required to maintain the weight required.

Density Used Density Recommended2.06 SG at 50° C 2.06 SG at 50° C

3. CONTINGENCY STOCKS.

Barite, lost circulation material, and base fluid stocks should be reviewed with the Elfsupervisor prior to starting each section. It is recommended to continue to keep these minimumcontingency stocks for each future 5 5/8” section.

Barite LCM BaseFluid

Starting Stock 341 MT 17.6 MT 125 m3

Minimum Contingency Stock 150 MT 6 MT 75 m3

4. RHEOLOGY.Yield points of 10 lb/100 ft2 gave adequate hole cleaning properties. A yield stress of 7 wasadequate for the low hole angles in this section. No tight hole attributable to cuttings beds orpoor hole cleaning was seen. Gel strengths were seen with flat 30 minute gels. Gels weretypically 14/26/30 to 15/32/37.

PV YP Yield StressUsed

Recommended ALAP 10 to 15 7 to 10

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5. EMULSIFIERS and HPHT.

There was minimal evaporation rates in this section, water additions were not required tomaintain the base fluid to water ratio (H/E).

Primary Emulsifier Electrical StabilityUsed EZ MUL 2F

Recommended EZ MUL 2F > 600

HPHT, ml. Temperature deg C.Used 3.0 200

Recommended < 6.0 200Used 4.0 190

Recommended < 6.0 190

6. ALKALINITY.

Continue to use lime to maintain an adequate alkalinity. ARCOSOLV produces results that aretypically three quarters to half that of Xylene / IPA solvents.

Excess lime kg/m3.UsedRecommended, engineers 5.0 to 10.0Recommended, program 2.0 to 3.0

7. EVAPORATION.

No evaporation detected or recorded on this section. No water additions required because ofwater addition to the system during a trip during a down pour.

8. BASE FLUID TO WATER RATIO AND WATER PHASE SALINITY.The base fluid to water ratio was decreased whilst wet tripping with the drains lined up toreturn to the pits. The mud bucket has been modified for use on the 3.1/2” pipe so that it isno longer necessary to line up on the pits when wet tripping.

The programmed water phase salinity was 250,000 mg/l chlorides. The actual salinity usedwas 175,000 - 190,000 mg/l chlorides. The hole was stable with the lower figure becausethe formation was primarily sandstone, claystone, and siltstone with occasional stringers ofcoal. Sandstone and coal are stable irregardless of the water phase salinity. The claystoneand siltstone were stable as demonstrated by a hole that was in gauge on the caliper logs.

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Base fluid/ Water ratio Water Phase Salinity.mg/l Chlorides

Used 80/20 to 84/ 16 145-190,00Recommended 80 / 20 to 85 / 15 225,000

9. LOW GRAVITY SOLIDS.Low Gravity solids kg/m3.

Used, corrected < 150Recommended < 150

10. SOLIDS CONTROL.Scalper Scalper No. 1 N0. 2 No. 3 No. 4 No. 5

Used at start. 12/30 12/30 250 185 185 250 150Used at end. 12/30 12/30 250 250 185 185 325

Recommendedat start.

12/30 12/30 250 250 185 185 185

Changing to : 12/30 12/30 250 250 250 250 325

The last screen, out of 3, was a 185 mesh screen on each of the main shakers. This is tominimise mud losses and to lower base fluid on cuttings figures.

11. BASE FLUID ON CUTTINGS.

Interval average 92.71 gm/kgWell average 73.28 gm/kg

The low rates of penetration with coreheads produced fine cuttings resulting in a higharithmetical average for the Base Fluid On Cuttings. Data from QTEC.

12. CEMENT DRILL OUT.

Drill out of cement.Use the XP-O7 mud to drill out the cement.

13. KILL MUD USED.

Type & Weight Used RecommendedXP-07, 50+m3 XP-07, 50 m3

0.3 SG above mud weight, up to killweight of 2.35 SG

0.31 SG above mud weight at 50º C

14. PIT MANAGEMENT.

Minor problems were encountered with the pits due to the large quantities of mud in the pits.These large quantities were maintained on site due to the possibility of losses in thePentland. This reduced the flexibility of the pit system. For example, the slug pit was filledwith pre-mix

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to control the weight after a trip. Remaining pre-mix had to put into a pit of mud so that a slug could be mixed during a trip. After the trip theslug pit was again used filled with pre-mix.

15 WELL SUSPENSION

On completion of the 5 5/8” hole abandonment programme 179 m3 (one hole volume) of XP-07 @ 2.17 sg was conditioned with 6.09 kg/m3 GELTONE IV, 13.45 kg/m3 INVERMUL-2F,13.90 kg/m3 Lime, 7.58 kg/m3 SUSPENTONE and 8.51 kg/m3 RM-63. This high viscositytemperature stable mud was displaced into the well above a bridge plug which had been set at5,030 metres and after running a debris cap the well was left suspended for future production.

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6.6 4 1/2” liner and cementing

A 4 1/2” liner will be run and cemented to the liner hanger. Running the liner: Prior to run the liner, the gel strength and yield point must both be

reduced, the yield point + 15 lb/100ft², and the 10’ gel to < 23 to avoid excessive surgepressures when running in. Pilot tests will be completed by the mud engineer to determinethe optimum treatment levels.

Cementing job: The liner will be cemented with a gas tight slurry 2.30 SG. The slurry volume will be calculated according with the calliper volume + 20% and anexcess corresponding at 100 metres of annulus volume (7”liner x 3 1/2” DP).

Slurry volume calculations (indicative, G4 Well ), 4 1/2” liner not set.

5 5/8” hole volume 16.03 l/m 5 5/8” x 4 1/2” annulus 5.73 l/m 7” x 4 1/2” annulus 6.39 l/m 7” x 3 1/2” DP annulus 10.08 l/m 4 1/2” inside volume 6.68 l/m 5” DP inside volume 9.14 l/m 3 1/2” DP inside volume 3.82 l/m Slurry volume ± 4 m3

Spacer volume 10 m3

Displacement ± 52 m3

Fluid designs. - spacer : Mud push WT DOWELL formulate spacer, 2.25 SG.

Fresh water 385 l/m3

D144 Defoamer 3 l/m3

D020 Bentonite 8 kg/m3

D143 FLAC 3.9 kg/m3

D135 Temp. Stabilizer 10.6 l/m3

D031 Barite 1676 kg/m3

F075N Surfactant 47 l/m3

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! Tail slurry: gas tight 2.30 SG.

G cement (Dyckerhoff)D066 Silica 350 kg/tDrill water 105 l/tD144 Antifoam 4.4 l/tD134 Gasblok 310 l/tD135 Temp.Stabilizer 31 l/tD121 Dispersant 10 kg/tD161 Retarder 160 l/tD076 Hematite 840 kg/t

Remarks:

1. all the formulations are indicative, they must be confirmed by laboratory testsperformed with samples coming from the rig before the cement jobs.

2. For an accurate displacement, the internal diameter of the casing must be

measured on 10% random joints.


Density 2.30 SG.Yield 1231 l/ton.Thickening time ± 8h00Fluid loss < 50ml.Free water < 0.1%Compressive strength at BHCT >300 bar 48 h

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7. Mechanisms of Wellbore Instability in the Transition Zone

Operational Considerations Symptoms and Remedial Action

Foreword

The intention of this chapter is to present the experience get during the first developmentwell drilled on ELGIN / FRANKLIN field with GALAXY 1 and MAGELLAN . This is donein order to make it available to the people in charge of such particular well , but also togenerate discussion on this up to date topic within drilling people with similar experience .Reservoirs in the Upper Jurassic Franklin sands and the Middle Jurassic Pentland sands arehot { 200°C } and deep { 5800 m}. The pressure gradient exhibits a marked increase belowthe Kimmeridge claystone with reservoir pressure of 1200 bars . These considerable drillingchallenges are compounded by the small margin – approximately 100 bars between fractureand pore pressure in the lowermost intervals .

7. 1 Well Instability :

Introduction :

The Kimmeridge Clay + Heather which is a known hydrocarbon bearing source rock , exhibits amode of behaviour when exposed to mud weights at or close to the fracture gradient variouslydescribed as Loss / Gain situation ; Ballooning ; Supercharging ; Thermal Effect or PlasticShales .Essentially the effect is for partial mud losses to occur to the claystone during circulation /drillingfollowed by an apparent influx when the pumps are off .With the well shut in on an apparent gainpreceded by losses , the annulus pressure recorded will be the difference between the static mudweight ( ESD ) and the dynamic friction losses ( ECD ) , i.e the additional back pressure applied tothe formation while drilling .

This type of behaviour could be described more graphically as well Instability .

Rig Crew’s experience shows Well Instability can be the beginning of a process with HPHT wellwhich can ultimately lead to a Well Control situation .The essential difficulty when faced with theloss / gain behaviour is the ability of rig crews to recognise and quantify the effect , thereby gainingthe necessary confidence to drill ahead .Guidelines need to be prepared which lead the crew through a logical process of Flow checking , Shutin , Recording , Calculating , Venting and Circulating . ( see Attachment “ Flow charts decision “ )

Coupled with the loss / gain problems the increasing background gas levels experiencedwithin the Kimmeridge which can be misinterpreted to indicate a balance or underbalancedrilling conditions and lead to :

Unnecessary Increases in Mud Weight .

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7. 2 How to recognise a well instability?

The well is considered unstable when:

1. A flow check is unstable ( well flowing )2. No pressure readings are shown at the annulus pressure gauge or at the stand pipe pressure

gauge3. Free gas ( gas degassing at the bell nipple ) are shown at the bottom’s up of the circulation

or in dynamic conditions without affecting the mud parameters .

7. 3 Reasons for well instability:

Two main reasons can lead to a well instability. Firstly the pore pressure in the reservoir is locallyhigher than the hydrostatic pressure applied by the mud , but due to a low permeability formation ,we are not in a kick situation : No pressure readings at surface.Secondly , the equivalent circulating density applied to the formation lead to seepage losses ( lossesof filtrate and possibility of losses of small quantities of whole mud to the borehole ). Theses smalllosses are difficult to detect on surface , but will generate a small gain of fluid when the circulationis stopped . A kind of circulation through this formation can be conceive in dynamic conditions .(see drawing ) Manifestation of well instabilityHigh formation pressure : the flow check showsmud returns , with no signs of stability (steady flow). The circulation of the bottom’s up will showhigh gas readings with a possibility free gas at surface.Gain and losses situation: ( known also as supercharging the formation ) the flow check showsmud returns, with a tendency of the flow check to decrease with time. Again the circulation of thebottom’s up will show high gas readings with a possibility of free gas at surface, this is due to thelarge surface area of the mud in contact with the gas bearing formation. Both manifestations can bethe same and trends are of a paramount importance to understand in which cases we can classify theinstability. Here some of the parameters we need to focus on :- Early detection of losses.- Annulus pressure losses ( PWD ) and , or Hydraulic simulation (ECDELF or BAROID

DFG).

From the above manifestations it is difficult to conclude if the well was unstable due acompartmentalised high pressure zone , from a losse and gain situation or from a natural depletiondue to a minor-supercharging generated in drilling conditions.( high ECD’s )

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7.4 GUIDE - LINES - EXPERIENCE

Nevertheless, all steps must be taken to avoid any supercharging of fluid to the formation , so toreduce the ECD.

• Maintain the ECD ; 5 points (0.05 sg) below the fracture pressure in any case• Use of a lower mud weight to drill the upper part of the transition zone (2.15 sg mud weight at

50ºC similar to 22 / 30c-G5 well i.e )• Use of low plastic viscosity and a yield point as low as possible without impairing the suspension

of the weighting material.• Expand flow check at the top of sands until reaching the stability of the well .• Bleed off process of Liquid and Mud influx with a maximum volume acceptable , repeat the

operation until stability .• Also, to better analyse an unstable well, it is recommended to increase the number of flow checks

while drilling through the Kimmerigde and Heather formations to spot any high pressure zone atonce.

A compromise must be found between the Time Factor ( see experience on wells drilled with thenew XP07 mud system ) , the rheology of the fluid , the back ground gas detected , the flow backvolume acceptable and Drilling practices such as systematic extended flow checks before pullingout of the hole .

Pulling out of hole :

A long series of flowchecks , short trips between bottom hole and shoe and bottom up circulationhad to be made before the whole drill string could be pulled out of the hole with the well stabilityjudged satisfactory enough by the Elf and drilling contractor’s supervisory personnel .[ The details of these Flow charts are shown on a schematic in appedix ]

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7.5 Matrix :

See attached a recap of the Indicators which are linked with a probably well instability .

8 1/2" Section - TRANSITION ZONE Well Instability Analysis

INDICATORS 22/30C -G4 22/30C -G5 22/30C -G6 29/5B - F1 29/5B - F2 29/5B - F3 22/30 C -G7

Back ground Gas >= @ 5 to 6% No No Yes No No No

Gas freeing at bell nipple - Gas Alarm on Yes No Yes Yes No No

Free gas after Bottom up Yes Yes Yes Yes No No

Intermediate Flow Check stable No Yes No No Yes Yes Yes

Duration of Connection Gas ( short ) Yes Yes Yes Yes Yes Yes

Seepages Losses reported > 0.5 m³/hour No No No No No Yes No

ECD >>or = @ 2.27 EMW Yes No No No No No No

Gas at the end of 12 1/4" phase-Caprock Yes Yes No Yes Yes No No

Trend of mud losses >> @ 100 litres / drilled meter Yes No Yes No No No No

Mud Weight @ 50°C 2.17 2.15 2.15 2.14 2.15 2.15 2.15

INSTABILITY PROBLEMS Yes No Yes Yes No No No

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7.6 Strategy :

A strategy has been decided before drilling through the transition zone [ see attachment ]

HT/HT Transition Zone on ELGINSTRATEGY

1 - Start drilling with SG=2.15 @ 50°C2 - Rheology => A.L.A.P with low gels (Gels 0/10/30 = 28/30/35) + Bridging agent3 - One connection gas by stand4 - Three Flow-Checks (base C.K, Kimm., Heather) - 1 hour or (5 to 10 bbls of mud flowback) - Note: well does not have to be stable to resume drilling.5 - Flow rate = 1500 l/min, ROP controlled to 5 m/hour6 - Gas monitoring with respect to G47 - HP/HT procedures according to JDM

LEGEND POTENTIAL EXPLANATION

PORE PRESSURE

SUPERCHARGING

PERCOLATION / DIFFUSIONLiquid - Condensate

CONTAMINATION

OVER-PRESSURE /SUPERCHARGE

SAGGING EFFECT

BALLOONING

THERMAL EFFECT

KIMMERIDGE CLAY

FRANKLIN SANDS

HP/HT TRANSITION ZONE

22/30c - G4 well (example)

PARAMETERSPP = 2.10 SGMud Weight = 2.17 @ 50°CECD @ 1500 L/MIN = 2.26 SGESD = 2.18 SGRheology: PV/YP > 45/17

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7.6.2 HP / HT Tripping Procedures :

DRDE9435.PPT

LOSSES/GAIN WHILE DRILLING HP/HT SECTION

DRILLING

Dynamic losses while drilling

Flow check : well flow ?

Monitor well on trip tank. Haswell flowed > 800 l (5 bbls) ?

Shut in well Record pressure

Compare with trends/volumelost since last stability

situation

Review situation

Supercharging suspected ?

Bleed off 800 l (5 bbls). Wellflow continues ?

Shut in well. Record pressure

Pressure < previous

Circulate bottoms up

Flow check : well flow ?

Follow well control procedure

See losses while drilling

Con

side

r red

ucin

g :

flow

rate

, RP

M, m

udw

eigh

t, rh

eolo

gie

No

No

YesNo

No

No

No

Yes

Yes

Yes

Yes

Yes

DRDE9435.PPT

LOSSES WHILE TRIPPING

Flow Check

Losses < 130 l/min(0.8 bbls/min)

Consult Aberdeenoperation

RIH to last casing shoe orstay in same level in OH

Observe while circulating


Spot LCM pill


Consider optionswith Aberdeen

operation

Cement plug andsqueeze

Wash to bottom

RIH to bottom

Follow losses/gainwhile drilling

No

No

YesNo

Yes

Yes

DRDE9435.PPT

HP/HT PROCEDURE WELL FLOWING

Drilling Tripping Out of hole

Raise kelly cockabove RT

Install open kelly cock Close B/S

Stop pump and RPM Weight > 25 KLBS Analyse situation

Close annular

Close annular Close PR abovetool joint

Open choke line

Open choke line

Record time andpressure Install and test Top drive

Close Kelly cock Equalise pressure andopen kelly cock

Install and test kickassembly Observe pressure

Equalise pressure andopen kelly cock Analyse situation

Analyse situation

Stripping

Bullheading

Off bottom kill

Case 1 (JDM)

Case 2 (JDM))

Case 3 (JDM)

Operation

YesNo

DRDE9435.PPT

LOSSES WHILE DRILLING

Flow check

Static losses

Adjust flow rate, RPMand parameters, …

etc. ...

Observe whilecirculating

Losses < 35 l/min (0.2bbls/min)

Reservoir pressure known

Reduce mud weight untiloptimal

Cure losses with LCM

Observe while circulating


Consider option withAberdeen operation

Cement plug

Drill plug


Consider option withAberdeen operation

Liner

Continue operation withaction to avoid further

losses

No

No

No

Yes

No

No

Yes

Yes

Yes

Yes

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7. 7 Fluid Simulator : ECDELF Software

7. 7. 1 Drilling Fluid Properties :

Conventional calculations of downhole pressure, which assume constant drilling fluid properties , areboth practical for day to day use and accurate enough for routine wells. Downhole static pressures areeasy to to calculate from mud weight measured at surface , while aditional pressures due to circulationcan be calculated using established relationships between pump rate and drilling fluid rheologicalproperties .However , mud properties do vary with downhole pressure and temperature , affecting the accuracy ofboth surface measurements and downhole estimations of mud weight and viscosity . In HPHT wellsthese variations can be significant because of the limited safety margins existing .

7 . 7. 2 Computing Downhole Fluid Pressure :

Instead of using EMW and ECD when calculating pressure in HPHT wells , it is more accurate toconsider static , dynamic and cuttings pressures as components of the total downhole fluid pressure .

Static Pressure :

Static pressure is computed by integration of hydrostatic pressures at each depth .To achieve this ,pressure – volume- temperature ( PVT) analysis is usually performed on the mud or the base oil . Manybase fluids used for oil- base muds have high compressibility compared with water based muds.By starting at the surface where the pressure and temperature are known , the local density of the fluidcan be computed. The predicted hydrostatic pressure and temperature permit the density at the nextdeeper level in the well to be computed .At the wellsite , the measured mud weight is used as thestarting point , increasing the accuracy of the initial conditions .With PVT data , static pressure at each depth can be computed with ECDELF software .

Dynamic pressure :

The dynamic pressure term is more comprehensive compare to the concept of ECD . It can account forannular pressure losses due to moving fluids , pipe velocity ( swab & surge ) and initial pressure fromstring acceleration when tripping and excess pressure required to break thixotropic gels . Predicting thedynamic contribution to the total pressure requires accurate modeling of the mud rheology .Depending on the fluid , the mud engineer selects an appropriate rheological model on the basis offitting a curve to data from HPHT viscometer tests ( FANN 70 ). Alternatively , the mud properties mayconform to established relationships , such as Bingham plastic mode or an empirical power law modelwith parameters chosen to represent the specific mud behaviour .

Modeling software such as the ECDELF program incorporating the algorithms for computingdynamic pressure. The advantage of these (over more complex models) is that the rheology parametersderived from them can be easily compared to wellsite measurements made using viscometer readings.

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Total Pressure :

The total pressure is the sum of static , dynamic and cuttings pressure . Expressing the downholepressure in this general form covers all phases of the operations . The total pressure can be balancedbetween the lowest safe static pressure and the highest acceptable circulating pressure by achieving acompatible balance of the different terms .The ability to compare actual behaviour to ECDELF sotfware and the PWD measurements at thewellsite is of great benefit in accurately predicting ECD ‘s.In practice the ECDELF program routinely achieves average differences of less than 4 % betweenpredicted and measured standpipe pressure .

7.8 Field Results - Conclusions :

No drilling related problems occurred during the ten HP/HT sections . Stable mud system , detaileddrilling program, correct execution on field and depth determination of the 9 7/8” casing shoe arefundamental. The following main conclusions and recommendations about fluid engineering andmanagement in HPHT wells derived from the experience obtained .

1. An accurate hydraulic program coupled with a temperature simulator is a critical tool .2. A methodology is required to accurately predict both a Constant hydrostatic overbalancewhen the well temperature profile is the geothermal gradient, and also a minimum acceptablehydrostatic overbalance in transient or steady state temperature conditions .3. Once the minimum overbalance is determined , the standard temperature for surface mudweight must be defined . { 50 °C } Thereafter the mud weight is maintained within a matrixwhich references the standard temperature.4. Field execution involves rigorous execution of procedures for evaluating mud characteristics, measuring mud weight , breaking circulation and tripping .5. The rig crew should be briefed by the fluid engineers on procedures that differ frompreviously accepted practice and the role that they have to play in management of the Bottom –Hole pressure .6. The mud temperature must be reported with any mud weight measurement .7. Due to the reduced hydrostatic overbalance , particular care must be exercised immediatelyafter stopping circulation .Any operations which have the effect of reducing the bottom holemud pressure must be carried out carefully .8. The difference between the equivalent circulating density ( ECD ) while breakingcirculation and ECD during normal circulation should be understood .9. Pump rate should be optimized , and a maximum set refined on an on-going basis .10. Any mud degradation must be anticipated before a long static period ( logging , trippingetc..) see Recommendation practices in HPHT .11. Continuity of key personnel is also important with a good communication .

Attachment :Measured ESD and ECD versus predicted are presented in this document . A recap per wellhas been done for each HP HT section .

.

Elgin Well 22/30C G6 - 8 1/2" drilling section13/07/2000

Based on 2.16 sg mud, PV / YP=69 / 22 - to be updated according to new mud properties

2.080

2.100

2.120

2.140

2.160

2.180

2.200

2.220

2.240

2.260

2.280

2.300

2.320

2.340

2.360

2.380

2.400

2.16 (mud density @ 50ºC)

2.182

920

LPM

85

RPM

2.1

Reservoir pore pressure 2.10sg

Fracturing pressure 2.39 sg

Circulat. / Drilling Tripping Static period11

00 L

PM

85 R

PM

ESD

Bottom hole pressure gradients on 22/30 C - G6 @ 5929 m

Supercharging ?

swab surge

1100

LPM

98

RPM

900

LPM

65

RPM

900

LPM

12

0 R

PM

2.16 SGESD

2.15

4 m

in /

STD 3 m

in /

STD

ESD

2.182

900

LPM

95

RPM

ECDELF

PWD

2.20

ELGIN 22/30c-G7 Hydraulics analysis 8½" holeReport Date Depth Depth Hole Flow RPM Pump Bit Jets BHA Ann vel Ann vel Mud Temp Mud Temp Temp rheology Pore ESD ESD ECD ECD FIT Formationnº TVD angle rate press nº nº DC DP Wt in in Wt out out MWD PV YP 0 gel press ELF PWD ELF PWD press comments

m m º lpm bars m/min m/min sg ºC sg ºC ºC cPo bs/100ftbs/100ft EMW EMW EMW EMW EMW EMW

5128 5040 2.35

54 23/09/1998 5142 5058 0.1 1500 80 248 9 2 x 20 9 89 64 2.15 46 2.15 51 145 51 15 12 2.167 2.241 2.231 Hidra

55 24/09/1998 5142 5058 0.1 50 17 12 "

56 25/09/1998 5165 5081 0.1 1100 120 174 10 6 x 12 10 65 47 2.15 40 2.15 45 153 53 15 12 2.167 2.228 2.229 "

57 26/09/1998 5259 5175 0.2 1100 120 171 10 6 x 12 10 65 47 2.15 49 2.15 51 53 17 14 2.165 2.230 Kimmeridge

58 27/09/1998 5357 5273 0.1 1100 120 172 10 6 x 12 10 65 47 2.15 48 2.15 50 53 16 13 2.164 2.230 Heather

59 28/09/1998 5463 5379 0.1 1100 120 168 10 6 x 12 10 65 47 2.15 50 2.15 52 53 16 15 2.166 2.232 Franklin C sand

60 29/09/1998 5622 5538 1100 120 169 10 6 x 12 10 65 47 2.15 51 2.15 53 61 21 15 2.166 2.232 Franklin B sand

61 30/09/1998 5724 5640 1100 125 181 10 6 x 12 10 65 47 2.15 51 2.15 52 65 23 17 2.167 2.249 Franklin A sand

62 01/10/1998 5724 5640 2.15 70 22 16 2.167

63 02/10/1998 5724 5640 2.15 70 22 16 2.167

64 03/10/1998 5724 5640 2.15 70 22 16 2.167

65 04/10/1998 5724 5640 1150 20 190 10 6 x 12 10 68 49 2.15 2.15 76 24 17

66 05/10/1998 5724 5640 1100 30 190 10 6 x 12 10 65 47 2.15 50 2.15 54 152 71 20 12 2.09 2.171 2.243 2.241

67 06/10/1998 5724 5640 70 21 13

68 07/10/1998 5724 5640

69 08/10/1998 5724 5640

Page 1

Equivalent Circulating Density on 22/30 C - G7

2.08

2.1

2.12

2.14

2.16

2.18

2.2

2.22

2.24

2.26

2.28

2.3

2.32

2.34

2.36

5142 5143 5165 5259 5357 5463 5622 5640 5724 5724Depth MD

Equ

ival

ent m

ud w

eigh

t

Supercharging

ECD ELF

Pore pressure

PWD

MW@50°C

ESD

Series7

Series8

Series9

Series10Kim

. @ 5

259

m

Hea

ther

@ 5

357

m

Fran

klin

C@

546

3 m

Pent

land

@ 5

700m

Supercharging area 2.25 EMW ??

8 1/2" Section

Fracture gradient 2.35EMW

Pore Pressure 2.09 EMW

Sheet2 Chart 1

Page 1

Bottom hole pressure gradient trends at 5530 metres, 5035 m TVDWell unstability with 2.15sg mud.

2.000

2.050

2.100

2.150

2.200

2.250

2.300

2.350

2.400

2.450

2.20

Frac pressure

Franklin sands pore pressure

Valhall pore pressure zone

Supercharging pressure

2.16

2.235

2.222.205

2.135

ESD

1500

LPM

13

0 R

PM

1500

LPM

60

RPM

800

LPM

0

RPM

POO

H 5

min

/std

800

LPM

POO

H

1 m

in/s

td

2.000

2.050

2.100

2.150

2.200

2.250

2.300

2.350

2.400

2.450

2.287

Frac pressure

Franklin sands pore pressure

Valhall pore pressure zone??

Supercharging pressure

2.225

2.2742.279 2.283

2.291

ESD

800

LPM

1000

LPM

1200

LPM

60

RPM

POO

H

1 m

in/s

td80

0 LP

M

- 03/02/99

1200

LPM

1200

LPM

90

RPM

ESD

2.225

Spot

420

mat

2.4

5sg

2.262.245

FRANKLIN 29/5b-F1 Hydraulics analysis 8½" holeReport Date Depth Depth Hole Flow RPM Pump Bit Jets BHA Ann vel Ann vel Mud Temp Mud Temp Temp Temp rheology Pore ESD ESD ECD ECD FIT Formation

nº TVD angle rate press nº nº DC DP Wt in in Wt out out PWD BHST PV YP 0 gel press ELF PWD ELF PWD press commentsm RT º lpm bars m/min m/min sg ºC sg ºC ºC ºC cPo lbs/100ft² lbs/100ft² EMW EMW EMW EMW EMW EMW

67 26/04/1998 5138 5016 3.0 1500 100 300 10 3 x 20 11 99 64 2.14 53 2.14 56 70 33 18 2.153 2.253 2.3369 28/04/1998 5138 5016 RIH @ 4479 m at 2.75 min/STD 12 2.14 24 18 153 70 33 18 2.211 2.19 2.3370 29/04/1998 5138 5016 RIH @ 5118 m at 2 min/STD 12 2.14 26 19 157 67 26 10 2.229 2.20 2.3370 29/04/1998 5138 5016 3.0 900 20 150 11 2x16 2x18 12 59 38 2.14 35 2.14 32 139 67 26 10 2.168 2.162 2.242 2.200 2.3370 29/04/1998 5140 5018 3.0 1000 50 155 11 2x16 2x18 12 66 43 2.14 38 2.14 39 144 67 26 10 2.162 2.162 2.242 2.223 2.3370 29/04/1998 5142 5020 3.0 1000 100 175 11 2x16 2x18 12 66 43 2.14 39 2.14 41 146 67 26 10 2.160 2.162 2.246 2.230 2.3370 29/04/1998 5143 5021 3.0 1100 15 183 11 2x16 2x18 12 72 47 2.14 42 2.14 44 146 67 26 10 2.158 2.165 2.237 2.220 2.3370 29/04/1998 5153 5031 3.0 1000 105 180 11 2x16 2x18 12 66 43 2.14 44 2.15 46 146 67 26 10 2.157 2.170 2.243 2.235 2.3370 29/04/1998 5161 5037 3.0 1100 105 202 11 2x16 2x18 12 72 47 2.14 45 2.15 48 150 62 21 10 2.155 n/a 2.242 2.240 2.3370 29/04/1998 5167 5043 3.0 1100 108 202 11 2x16 2x18 12 72 47 2.14 46 2.14 49 150 158 62 21 12 2.16 2.154 2.17 2.240 2.237 2.33 Sola71 30/04/1998 5209 5087 3.0 1100 110 196 11 2x16 2x18 12 72 47 2.14 46 2.13 50 152 159 54 22 10 2.18 2.154 n/a 2.236 2.237 2.33 Heather72 01/05/1998 5247 5125 3.5 1127 140 191 11 2x16 2x18 12 74 48 2.14 46 2.14 49 154 161 54 21 13 2.16 2.155 n/a 2.233 2.227 2.3373 02/05/1998 5293 5171 3.5 1120 139 194 11 2x16 2x18 12 74 48 2.14 46 2.14 52 163 50 21 12 2.14 2.153 n/a 2.231 n/a 2.33 Franklin C74 03/05/1998 5357 5235 3.5 1100 98 210 11 2x16 2x18 12 72 47 2.15 47 2.15 52 167 52 18 11 2.13 2.164 n/a 2.237 n/a 2.3380 09/05/1998 5418 5294 3.5 915 100 149 12 TFA 0.75 13 68 39 2.15 38 2.15 46 170 53 17 10 2.11 2.166 2.226 n/a 2.3383 12/05/1998 5419 5295 3.5 1090 101 195 13 4x10+4x12 14 72 47 2.15 35 2.15 39 157 170 53 18 12 2.11 2.166 n/a 2.235 n/a 2.3384 13/05/1998 5452 5329 3.8 1115 100 181 13 4x10+4x12 14 73 48 2.14 44 2.14 49 158 171 50 16 14 2.06 2.158 2.15 2.216 2.197 2.3385 14/05/1998 5544 5422 3.8 1100 100 180 13 4x10+4x12 14 72 47 2.14 48 2.14 52 162 177 62 18 14 2.07 2.155 n/a 2.216 2.210 2.33 Franklin A86 15/05/1998 5637 5514 3.8 1100 130 193 13 4x10+4x12 14 72 47 2.15 49 2.15 55 165 182 62 19 12 2.04 2.167 n/a 2.238 2.223 2.33 Pentland87 16/05/1998 5663 5540 1100 129 210 13 4x10+4x12 14 72 47 2.15 50 2.15 56 167 183 63 19 10 2.163 n/a 2.240 2.223 2.3392 21/05/1998 5677.5 5555 900 120 155 12R1 0.76in² 15 59 38 2.15 37 2.15 40 60 18 10 2.173 2.245 n/a 2.33 Pentland95 24/05/1998 5701.0 5578 920 130 146 14 0.76in² 16 61 39 2.15 37 2.15 40 61 18 9 2.173 2.254 n/a 2.33 Pentland96 25/05/1998 5701.5 5579 900 130 148 14 0.76in² 16 59 38 2.15 40 2.15 44 61 18 9 2.171 2.251 n/a 2.33 Pentland99 28/05/1998 5707.0 5585 900 120 155 14 0.76in² 17 59 38 2.15 40 2.15 45 63 19 12 2.170 2.251 n/a 2.33 Pentland

100 29/05/1998 5710.8 5589 900 120 155 14 0.76in² 17 59 38 2.15 40 2.15 45 64 20 14 2.170 2.228 n/a 2.33 Pentland102 31/05/1998 5718.0 5595 1030 80/120 180 14R2 0.76in² 18 68 44 2.15 45 2.15 50 69 19 12 2.167 2.226 n/a Pentland105 03/06/1998 5723.0 5600 3.1 1040 120 206 15 4 x 13 19 68 44 2.15 42 2.15 47 163 71 18 13 2.171 2.234 2.240 Pentland106 04/06/1998 5756.0 5632 3.1 1100 140 233 15 4 x 13 19 72 47 2.15 53 2.15 59 67 20 13 2.162 2.228 Pentland108 06/06/1998 5756.0 5632 16 0.76in² 20 2.15 64 20 13 2.170 2.233109 07/06/1998 5765.0 5641 1000 130 198 16 0.76in² 20 66 43 2.15 43 2.15 44 63 19 12 2.170 2.233 Pentland110 08/06/1998 5765 5641 16 0.76in² 20 2.15 65 19 12 2.04111 09/06/1998 5765 5641 17 4 x 14 21 2.15 67 20 13112 10/06/1998 5770 5647 1155 142 240 17 4 x 14 21 76 49 2.15 41 2.15 43 164 66 20 15 2.03 2.173 n/a 2.247 2.25 2.33113 11/06/1998 5820 5697 1120 141 240 17 4 x 14 21 74 48 2.15 51 2.15 56 171 190 66 18 14 2.03 2.163 n/a 2.236 2.24 2.33114 12/06/1998 5879 5756 1155 140 233 17 4 x 14 21 76 49 2.15 53 2.15 56 195 64 21 14 1.98 2.162 n/a 2.236 n/a 2.33115 13/06/1998 5927 5804 1170 140 231 17 4 x 14 21 77 50 2.15 56 2.15 60 198 65 19 13 1.97 2.162 n/a 2.245 n/a 2.33116 14/06/1998 5927 5804117 15/06/1998 5927 5804 195118 16/06/1998 5927 5804 2.166119 17/06/1998 5927 5804 197120 18/06/1998 5927 5804121 19/06/1998 5927 5804122 20/06/1998 5927 5804 1150 50 177 17R 4 x 14 22 76 49 2.15 40 2.15 42 70 26 9 2.17 2.244 2.33123 21/06/1998 5927 5804

Total 22/06/1998 5927 580423/06/1998 5927 580424/06/1998 5927 5804

MEASURED AND CALCULATED ANNULAR PRESSURE

Franklin Well 29/5B-F1 8 1/2" drilling section09/07/2000

2.120

2.140

2.160

2.180

2.200

2.220

2.240

2.260

2.280

2.300

2.320

2.340

2.173 2.173

ESD

Supercharging ??

ESD

ECDELFPWD

BHCT @ MWD : 164°C

Temperature out : 43°C

Page 1

Equivalent Circulating Density on 29/5B - F1

2.1

2.12

2.14

2.16

2.18

2.2

2.22

2.24

2.26

2.28

2.3

2.32

5140 5143 5161 5167 5209 5247 5293 5357 5418 5452 5544 5637 5677 5701 5701 5707 5710 5718 5723 5756 5770 5840 5850 5860 5900 5937Depth MD

Equ

ival

ent m

ud w

eigh

t

Supercharging

ECD ELF

Pore pressure

PWD

MW@50°C

ESD

Series7

Series8

Series9

Series10

Sola

@ 5

167

m

Hea

ther

@ 5

209

m

Fran

klin

C@

529

3 m

Pent

land

@ 5

637m

Supercharging area ???

8 1/2" Section


Pore Pressure 2.13 EMW

Seep

ages

Los

ses 2

00l/h

our

ESD

with

MD

T 2.

172

@ 5

876

m M

D

Hydrau Chart 1

29/2b-F2 - 8 ½ - Pressure

Pore Press. - MDTESD - ECDELFECD - ECDELF

Hydrau Chart 1

Pore Press. - MDTESD - ECDELFECD - ECDELFLOT

Pore Press.well design ECD - PWDLOTMud weight at 50ºC

Page 1

Equivalent Circulating Density on 29/4D - 4

2.05

2.07

2.09

2.11

2.13

2.15

2.17

2.19

2.21

2.23

2.25

2.27

2.29

2.31

2.33

2.35

2.37

2.39

5175 5256 5315 5375 5424 5471 5508 5550 5598 5606 5613 5658 5712 5824 5863 5943 5982 6024 6028 6032 6036 6040 6044 6041Depth MD

Equ

ival

ent m

ud w

eigh

t

Supercharging

ECD ELF

Pore pressure

PWD

MW@50°C

ESD

Series7

Series8

Series9

Series10

Sola

@ 5

271m

Val

hall

@ 5

330m

Kim

mer

@54

30 m

Hea

ther

@54

73 m

Supercharging area !!!

8 1/2" Section


Pore Pressure 2.06 EMWSe

epag

es L

osse

s 1 b

bl /

hour

Fulm

ar @

5591

m

Cor

e #1

-flow

=750

l/min

Cor

e #2

-flow

=100

0l/m

in

Cor

e #3

/4/5

-flow

=100

0l/m

in

Dri

lling

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7 .10 8 ½” Section P.W.D Interpretation :

Foreword:

A massive data base of valuable information were recorded on this run.The PWD memory gauge gave the same information than the real time ECD’s data. In addition staticdensities and surge & swab were recorded.While we drilled from 5284 to 5687 metres MD, real time data were pulsed from top to 5654 m (92% of metrage). 100% of the run was recorded on a memory gauge.

7.10.1 SURGE and SWAB PRESSURE

Swab pressure are totally in accordance with the ECDELF simulation: Swab versus Trippingspeed.Note this pressures are calculated or recorded at the bit. Therefor, only part of the this negativepulses are transmitted to the bottom of the hole.

Surge pressure are within one point of density

Surge & Sw ab Pressure

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

0.12

0 1 2 3 4 5 6 7 8

M in/stand

EMW

PWD surgeECDELF surgePWD SwabECDELF swabPWD Pump out 200 lit/min

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7.10.2. EQUIVALENT STATIC DENSITIES

The ESD predicted by ECDELF are 0.01sg.higher than the recorded PWD measurements.The temperature modelling on ECDELF must be improved to better match the recorded data. This isnow possible with the recorded temperature while pulling out of the hole.The average ECD showed an ESD at 2.155sg, when the dispersion of data showed the difficulties tomaintan a 2.15sg at 50ºC in the pit, mud weight IN varying from 2.14 to 2.165sg. The informationwas used to reinforce the communication between the MWD engineers, loggers and rig crew on thenecessity to maintain a specific and accurate mud weight.PWD on line data are difficult to pick up by the engineer and must be used with care.

Equivalent Static densities

2.11

2.13

2.15

2.17

2.19

2.21

5200 5300 5400 5500 5600 5700 5800M easured depth

ESD (sg)

PWD recordedECEDELFPWD on line

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7 .10.3 EQUIVALENTCIRCULATING DENSITIES :

The values of the PWD are in line with the ECDELF at the flow rate of interest 900 to 1200 lit/min.The heating regime of the well must reach a stable phase, before ECDELF is fully accurate. For thisgraph, the temperatures were adjusted to obtain the same static densities, so flow rate and RPM arethe only parameters.The software predict too high values at low flow rate, certainly due to the difficulties to measure therheology accurately in the laboratory at low shear rate. This is not of a great concern in our wells, asthis flow rate will develop low ECD’s in the well.

2.18

2.19

2.2

2.21

2.22

2.23

2.24

0 200 400 600 800 1000 1200 1400Flow rate (lpm)

ECD increase PWD

ECDELF80 rpm

80 rpm40 rpm

80 rpm60 rpm

80 rpm

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7 .10.4 TEMPERATURE :

Maximum BHCT: 167ºC at 5687 m RKB while drilling, this temperature increased to 171ºC after 2hours of flow check.

29/5b-F5 - 8 ½ -Tem perature

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000M easured depth

Temperature (º

PWD recorded POOHBHST

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7 .10 . 5 LEAK-OFF TEST

The values of the leak-off test reflects the surface data.with a static density at 2.162sg, maximum at2.306sg (Leak-off), and a stabilized value at 2.282sg.All the pressure is transmitted trough the mud.

PW D leakoff test

2.14

2.16

2.18

2.2

2.22

2.24

2.26

2.28

2.3

2.32

26/08/99 01:12 26/08/99 01:19 26/08/99 01:26 26/08/99 01:33 26/08/99 01:40 26/08/99 01:48

EMW sg

Pressure While Drilling data and software.

1. Conclusions

The annulus pressure losses are of a paramount importance in the 8 ½ section where the pore and thefracturing pressure converge. The PWD tool, measuring the Equivalent Circulating and StaticDensities (ECD and ESD) is a precious guide to define the flow rate to drill the high pressurezone.Unfortunately, the tool stop working soon after we started drilling. The coverage is only 12%of the metrage drilled in the 8 ½ section, which is detrimental to the success of the wholeoperations.It is important to keep using the PWD tool to measure the annulus pressure losses, becausemany hidden parameters can be detected from this tool, i. e. gelation of the drilling fluid,annulus blockage, barite sagging,… that will adversely affect the ECD.

SOFTWARE: ECDELF and BAROID DFG were able to forecast the ECD within 0.01sg (1 pointof density) at the nominal flow rate but became inaccurate at higher flow rates and when the piperotation was on.

Here is some of the lessons learned while drilling the first appraisal well , followed by atypical example of the use of the PWD.

1.1 Equivalent Circulating Densities

Be aware of high ECD when restarting the circulation after a round trip, with additionalpressure losses in the annulus ( + 0.02 / 0.03 sg ) due to:• heavy mud used to slug the drill pipe while pulling out of the hole,.• a viscous and gelled mud due to lower temperature in the well plus heat degradation of the

mud products at the bottom of the well,• a higher mud weight due to overall decrease in temperature in the well,• the sagging or the settling of barite in the lower part of the well.Therefor a special care must be taken when resuming the circulation after a round trip anddepending on the extent of the above manifestations, flow rate must be adjusted. Pit levelsand flow out are the keys parameters.For a rule of thumb, flow rate had to be decreased by 30% or rotation left at 20 RPM until thefirst bottom up was out of the hole.

Rotation: The rotation of the pipes induces a turbulent component in the flow leading to anhigher annulus pressure losses. With a rule of thumb of:0.01sg for 60 RPM,0.02sg for 120 RPM,0.03sg for 180 RPM.

Equivalent Circulating Densities measured (PWD) must be compared to ECDELF andBAROID DFG simulations to clarify the validity of the software.

1.2 Surge and Swab

Running In the Hole at a controlled speed (1.5 min per stand or below) induces a surge withan equivalent mud weight of 2.25sg.

Pumping out of the hole: the flow rate (250 lit/min when POOH at 5 minutes/stand) applied apressure that compensates the swabbing effect of the removal of the drill pipes. A too highflow rate is not necessary.

Pulling out of the hole: the swab pressure are controlled with very low to ultra low speed ofpipes motion. The decrease in pressure brings the hydrostatic to a level which is still verycomfortable in front of the reservoir. Nevertheless, the unknown pore pressure of thetransition zone (higher pressure?) must be treated differently.

Software like ENERTECH WFSURGE can help in defining the optimum tripping speed.The impact in time savings is forecast to be above 24 hours per well.

1.3 PWD utilisation

SPERRY-SUN must improve the reliability of the tool, which is functioning for a too shortperiod of time while drilling the high pressure, high temperature zone (only 12% of themetrage drilled). See table here below.

Drilling bit Metrage from to PWD data from to CoverageSMITH M 37 P 5183 to 5523 m 5183 to 5185 m 1 %HYCALOG DS56JNV 5555 to 5560 m 5555 to 5560 m. 100 %HYCALOG DS56JNVrerun

5692 to 5884 m 5692 to 5750 m 30 %

TOTAL 537 m drilled 65 m of data 12 % coverage

2. PWD run 03/09/97 to 05/09/97

1.1 ECD while drilling

03/09/97 22:30 Circulation at 5533 metres of 25 m3 heavy mud 2.31sg at 50ºC.Flow RPM MW in Temp In BH temp ESD ECDlit/min sg at 50ºC ºC ºC sg sg800 30 2.19 30 168 2.225 2.29maxiThe maximum of the Equivalent circulating density was recorded when circulating with :• a cold mud (higher mud weight and higher rheology)• circulating out the 25 m³ of heavy mud spotted to control a well instability. 04/09/97 02:00 Heavy mud out of the hole Flow RPM MW in Temp In BH temp ESD ECD lit/min sg at 50ºC ºC ºC sg sg 800 20 2.19 44 140 2.205 2.245 As soon as the heavy mud was out of the hole the ECD decrease rapidly, and the flow ratecan be adjusted to higher values. 04/09/97 02:30 Drill out core, circulate bottom up Flow RPM MW in Temp In BH temp ESD ECD lit/min sg at 50ºC ºC ºC sg sg 1000 80 2.19 43 147 2.205 2.27 1000 120 2.19 43 152 2.205 2.27

1000 20 2.19 46 150 2.21 2.25 The annulus pressure losses are greatly affected by the rotation of the drill pipes (refer toDavid Bertin report). The ECD increases circa 1 point of density (0.01sg) per 60 RPM

04/09/97 02:30 Circulate bottom up at 5050 m. Flow RPM MW in Temp In BH temp ESD ECD lit/min sg at 50ºC ºC ºC sg sg 1000 0 2.19 35 143 2.205 2.245 1100 0 2.19 43 142 2.205 2.255 1200 0 2.19 44 141 2.205 2.263 1300 0 2.19 45 140 2.205 2.27 The above values were compared to the ECDELF and BAROID software.

ECDELF and BAROID DFG software still needdevelopments. In this particular example, ECD valuesare corrected at 1000 to 1200 litre/minute, but atlower flow rate, the ECD simulations are too high andat higher flow rate the ECD simulation are too lowwhich can be dangerous when applied to the well:start of a losses and gain instability. After theses measurements, the flow rate was kept at1000 lit /min until reaching the end of the section. Thislow flow rate in 8 ½ section proved to be adequate forboth cleaning the hole and cooling down the core barrelor the PDC bit and had no adverse effect on theperformance of the drilling bits.

2.1 Surge pressures 03/09/97 Running in the hole, shoe at 5179 metres. Depth Tripping speed Flow surge press. ESD at depth ESD at shoe m min/stand lit/min sg sg sg 2740 uncontrolled 0 + 0.13 2.34 2.28 4500 2 0 + 0.02 2.23 2.23 5020 1.5 0 + 0.04 2.25 2.25 5200 3 0 + 0.03 2.24 2.24 5400 5 0 + 0.02 2.25 2.25*• * 25 m3 heavy mud 2.31 sg at 50ºC on bottom.All measurement are showing that we are far from the fracturing pressure at 2.31sg, speciallywhen we are controlling the descent of the pipes inside the hole.

2.2 Swab pressures04/09/97 POOH

Depth Tripping speed Flow swab press. ESD at depth ESD at shoem min/stand lit/min sg sg sg5200 5 250 0.00 2.21 2.214700 5 0 - 0.02 2.19 2.193400 3 0 - 0.035 2.175 2.19

ECD PW D versus sim ulations

y = 8E-05x + 2.1681

2.2

2.22

2.24

2.26

2.28

2.3

2.32

400 900 1400

All theses measurements are again showing that we are far from the equivalent pore pressureat 2.09sg (EMW at RKB) maximum measured.

The ultra low speed to pull out of the hole could be increased slightly without impairing thewell stability.

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8. COMPLETION - Non - Perforated Well :

8.1 Purpose

The main aim is to safely and successfully run a completion string into the well whichcan subsenquently be used as an ELGIN/FRANKLIN gas condensate producer . Thefollowing procedure described the preparation to turn the well over kill mud toinhibited fresh water .

8.2 Well Clean up Procedure :

Prior to running the clean-up string a mud conditioning trip will be carried out.

Inflow Testing General

One of the key areas associated with using an underbalanced annular fluid, is the well integrity. It istherefore of paramount importance that the integrity of the well be fully proven prior to running thecompletion string in a 1 SG annular fluid.The following areas are key:-

• Good cement job on the liners• Casing / liner pressure tests are good• Cement bond logs have been made and show a good cement job• Inflow test to the full underbalance of 1 SG fluid. The only true representation of the well integrity test will be when the final clean up circulation hasbeen made and the well bore has been fully displaced to 1 SG water. This represents the finalhydrostatic that will be left in the well. Therefore the primary method for the well integrity check will be to run the clean up string asdescribed below. One of the major benefits is that there will be pipe on bottom at all times duringthe inflow test hence the well can be better controlled in the event of any influx. This string designwill also be enhanced with the following:- • A pressure/ temperature measurement tool will be run ( PWD tool ).• Use of a Multi - Function circulating tool.• A float will be run above the circulating tool.• Sub run for a drop in check valve.• The well will be monitored until the bottom hole temperature returns to the original undisturbed

temperature prior to pulling the string. During the well clean up/ inflow test the following points need to be carefully noted and addressed:- • The fresh water used in the well bore will be underbalanced to the reservoir by 575 bars.

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• The clean up string will be left on bottom afterthe final circulation has been made, until the well temperature returns to the un-disturbedBHT prior to pulling the string out of the hole.

( 1 SG fluid in the well bore )• Pressure and temperature PWD tool will be run to confirm the bottom hole conditions. • The BOP and well head cavities will be jetted to ensure all traces of mud solids are

removed. • The rig choke and kill lines and the rig choke and kill manifolds will have to be fully

flushed in order to ensure that the no mud contamination takes place with the 1 SG fluid.

Displacement to Completion fluid

To displace the heavy XP07 mud ( 2.12 SG ) to freshwater it will be necessary to displace initially toan intermediate XP 07 mud of 1.60 SG due to pump pressure limitations. The first 50 bbls of thelighter mud should be viscosified to minimise any channelling. Once the well is stabilised with the1.60 SG mud it will then be displaced to seawater by pumping a sequence of pills ahead of theseawater to ensure the well is cleaned up as efficiently as possible in the minimum amount ofcirculating time. The well will then be turned over to the inhibited fresh water completion fluid.Objectives

1. Displace the XP07 based mud of the well with a minimal interface.2. Change the wettability of all downhole surfaces from XP07 wet to water wet.3. Prevent the discharge of mud and/or contaminated water to the environment.4. Minimise the requirement for backloading “oily” water for onshore disposal.5. Remove pipe scale, solids, mud solids and other contaminants from the wellbore.

Initial Rig Preparation

All rig pits, ditches and lines should be cleaned using degreasing solvents and detergents. Theyshould be rinsed out and squeezed dry. If it is practical, lines should be opened to check for any mudsolids that might have settled in them.

All the pits, sandtraps and under the shale shakers should be cleaned out and washed down usinghigh pressure cleaning equipment. All fluid transfer lines should be circulated to remove compactedmud from bends and fittings.

In the pit room, all gratings should be cleaned, all the lights and beams should be washed down.

The success of the well clean-up will be influenced by the cleanliness of the surface equipment. Itis therefore, important to ensure that the pits and surface lines have been thoroughly cleaned. Belowis a list for the mud engineer and derrickman.

To ensure cleanliness of these items after normal pit cleaning a sweep of 200 bbls seawatercontaining four drums of Detergent should be circulated throughout the above system and any otherareas / equipment where completion fluids will be stored as fast as is possible.

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All dump valves should have the seals and valve seats checked to ensure that they are in good order.They should be greased to ensure a good seal and if possible be manually guided and checked whenbeing closed to ensure a perfect fit.

All ditch gates should be sealed with silicon on each side of the gate. This will need to be replaced ifthe gate is opened.

UNDER NO CIRCUMSTANCES SHOULD BARITE, BENTONITE OR POLYMER BE USED TOSEAL ANYTHING.

All pump packing should be examined and if necessary replaced. Any suspect packing is bestreplaced ahead of time.

Packing should be lubricated with grease. Water can all too easily leak into the system and canobscure brine leaks. Packing should be lubricated on a regular basis to ensure minimal losses.

The clean-up fluids will be most effective if pumped in turbulent flow. An MFCT (Multi-functionalcirculating tool) is included in the string and positioned above the top of the 7” liner.

Consideration should be given to functioning the BOP’s after displacing the XP07 mud to clean outthe cavities if practicable.

8.1 1 Mud Conditioning :

Barriers in place :

Tubing Annulus

Liner Liner

Kill Weight Fluid ( SBM ) Kill Weight Fluid ( SBM)

BOP BOP

1. Make up Bottom Hole Assembly and run in hole on 3-1/2” WT-31 drill pipe. BHA to be basedon 1 PDC 5 5/8” + 1 Bit sub 4 3/8” + 2 Drill Collars 4 3/8” + 1 jar 4 ¼” + 2 Drill Collars + xDrill Pipe 3 ½” + 1 Crossover + 1 Drill Pipe HW 5” + 1 DHCV + Drill Pipe HW 5”+ Drill pipe5”.

2. Run in hole with 5” Drill Pipe to top of liner packer.

3. Slowly enter liner and run in hole to 5830 m.

4. Circulate and condition mud until mud properties are acceptable .The treatment consists to addpremix mud to reduce rheology and Gels .( SG = 2.12 , PV = 45 / 50 , YV = 20 / 25 , Gels = 18/ 25 / 35

5. Pull out of hole with mud conditioning string.

6. Clean-up and displace to Completion fluid

7 Make up Bottom Hole Assembly and run in hole. Clean up string to be based on 1 PDC 5 5/8” +1 Bit sub 4 3/8” + x Drill Pipe 3 ½” + 1 Crossover + 1 MFCT tool + 1 9 7/8” SPS Eliminator +

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1 float collar + x Drill Pipe 5” + 1 PWD tool + x DrillPipe 5” + 1 DHCV + 1 10 3/4” SPS Eliminator + Drill Pipe 5” to surface.

8 Run in with the clean out assembly and position circulating valve above the top of the 7 “ linertop.

9 Circulate the well to an intermediate weighted mud system. The first 20 m3 of 1.60 SG mudshould be viscosified to prevent channelling. Circulating rates will be determined by pumppressure limitations. As the light mud reaches the bit the highest mud weight differential will beseen (- 225 bars ). When the light mud passes into the 9 7/8” casing the circulating sub shouldbe opened (set down weight on liner top to open the circulating tool) and the circulating rateincreased to a maximum of 1000 / 1200 ltrs/min dependent on pump pressure limitations.

10 Inflow test the well. Activate the PWD tool periodically to gain a true indication as to thebottom hole responses

11 Make a final circulation and monitor for any abnormal returns.

When the 1.60 SG mud has been circulated around and the well is stable a series of pills, will becirculated ahead of the seawater. Before any of the pills are pumped the circulating system tobe used should be checked and cleaned as necessary. As the first pill reaches the bit the pressuredifferential will be at the maximum, in the region of - 575 bars in hydrostatic alone. When thetail of the last pill passes into the 9 7/8” casing the circulating sub should be opened (set downweight on liner top to open the circulating tool) and the rate increased to a maximum of xxltrs/min dependent on pressure limitations. It is important to ensure turbulent flow is inducedfor a successful clean up.

See Pill formulation & procedure - Attachment n°1 .

Displace with seawater at maximum rate with reciprocation and occasional rotation. NTU andPPM readings should be taken during the displacement.

Once NTU and PPM readings are acceptable, stop pumping and inflow test the well. Activatethe PWD tool periodically to gain a true indication as to the bottom hole responses

Make a final circulation and monitor for any abnormal returns.

Displace the seawater with the inhibited fresh water completion fluid.

Inflow test the well. Activate the PWD tool periodically to gain a true indication as to thebottom hole responses.

Make a final circulation and monitor for any abnormal returns.

Pull out of hole with the clean up string carefully monitoring hole volumes.

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Well Technical data - Attachment 1 -

1 . Well data and Casing string :

1 . 1 Well Data :

Liner 7” 42.5 # set at 5883 m MD , top liner Packer at 5038 m MD BRT .Bridge Plug at 5830 mDepth : 6103 m MD -BHST = 197 °C-Pressure = 1162 Bars ( 2.05 EMW ) at TBA top sand A.

1 . 2 Casing :

Interval( m RKB )

Burst( Bar )

Collapse( Bar )

Drift( “ )

ID( “ )

10 ¾” HWST 1 - P110 110.2# 3512 m 1296 1337 8.5 8.74

9 7/8 “ VAM Top - Q125 66.9# 5038 m 1021 890 8.5 8.58

7 “Liner VAM Top 25% Cr42.7#

5830 m 1347 1402 5.625 5.78

String composition N/A

Tubing - Drill pipe 3 1/2" 15.8# Hydril PH6 31/2"17.05Hydril

27/8" New10.40 # S135

Collapse resistance 22,330 psi 24,410 psi 29716 psiMin. Burstresistance

22,610 psi 25,180 psi 29747 psi

Tensile capacity 430,000 lbs 470,000 lbs 386,000 lbsDrift 2.423in 2.315in 2.151in bodyID coupling 2.548 in 2.440 in 1.5 inODcouplings 4.500 in 4.563 in 3.125 inBody ID 2.548 in 2.440 in 2.151 inCapacity 2.36 l/m

Optimum make-uptorque

ft.lbs ft.lbs ft.lbs

Maximum make-up torque ft.lbs ft.lbs 6000 ft.lbsTorsional Yield = 10400 ft.lbs

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2 - Well Bore Clean -up programme :

2 . 1 . Purpose :

To displace the heavy SBM mud ( XP07 ) in the hole with chemicals washers + InhibitedDrill Water

2 . 2 . Overview of Objectives :

The displacement recommendations are designed to achieve the following objectives :

a ) remove mud , mud solids , rust and others contaminants from the wellbore .

b) perform an inflow test under water .c ) clean the well before running the DST string .

There are differents objectives that must be met to obtain a successful casing cleaningoperation .

First , one must choose wash pills that have good mud dissolving properties .Secondly , the velocity of the washing/displacing fluids are of vital importance ,this means that the cleaning efficiency of the wash pills are a function of the velocity ;higher velocity , better cleaning .Third , reciprocating the drill pipe during the displacing and cleaning operation willreduce the possibility of mud settling on the drill pipe and casing at the lower side of thewell .

2. 3 . Check List for casing cleaning operations :

This check list contains a brief description of the design parameters that the casingcleaning procedures are based upon .

Mud properties : ( at the suspension )

Mud Type : SBM ( XP07 ) mud .Density : 2.17 (SG)Plastic Viscosity : 87 @ 50°CYield point : 43 @ 50° CGels : 39 / 70% solids : 36 %.

Hydraulic considerations :

It’s a critical issue . An optimum flow rate is required to ensure a turbulent flow for eachspacer in the annulus . But , the maximum flow rate is limited by the maximum allowablepressure losses supplied by the rig pumps .

Then ,the displacement of the SBM ( 2.12 SG ) will be facilitated by circulating anintermediate SBM with 1.60 SG in the hole .Once the well is stabilised with 1.60 SG mud it

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will be displaced to fresh water by pumping asequence of pills ahead of the water to ensure the well is cleaned up as efficiently .Circulation to be performed with well closed in and returns taken through a wide openchoke . A SPP schedule will be followed as per well control .

Hydraulic calculations are not completed , the present table is to give the range of pressureand the limitation at TD .

TD = 5830 m - TVD = 5688 m Mud 2.17SG Mud 1.60 SG Water 1.00 SG

Pore pressure ( 2.05 EMW ) 1165 bars 1165 bars 1165 bars

Hydrostatic pressure with Mud orWater

1222 bars 949 bars 568 bars

Differential pressure / Pore pressure + 57 bars - 216 bars - 597 bars

U-tube effect to displace the fluid N/A + 273 bars + 381 bars

P-additional to U-tube effect to displacethe fluid

+/- 200 bars at400 l/min

+/- 160 bars at 900 l/min

Pipe movement : Reciprocating and Rotation ( 20 RPM ) ..Use of Rig pumps will be limited to the maximum pressure allowable and the finaldisplacement will be done with Halliburton cementing pump.

2 . 4 Displacement Procedure :

Once the well has been displaced to 1.60 SG mud with an acceptable flow check .

2 . 4 . 1 Flushing of surface equipment : ( Key of success during clean up )

Prior to start casing cleaning operation , ensure that all mud pumps ( suction lines ) ,relevant circulating lines , stand pipe manifold , RISER and mud return system( degasser , trip tank , flow line , gumbo box and mud ditch ) are completely clear of mudby using seawater with drilling Detergent / Washers or high pressure water guns asrequired

Typical Cleaning Procedure for BOP area :

Wellhead / BOP / Riser :

• Run wash tool into the wellhead / BOP / Riser to +/- 60 m . Run Well patroller 2 standsbelow wash tool.

• Drain BOP and riser prior jetting BOP cavities and wellhead with freash water /Baraclean ( rig wash ).

• Jet BOP’s and riser .• Pull back until rams are across the drillpipe and function pipe rams twice . Do not

function shear rams .

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• Run in hole and jet BOP’s and riser .• Run +/- 60 m and displace to filtered fresh water .• Pull wash tool assembly out of hole . Check Well patroller for debris . 2 . 4 . 2 Condition the Mud ( at 195°C BHST ) The Intermediate drilling mud will be conditioned after displacing. When circulation willbe established , adjust mud rheology to be sure to remove and disperse solids from thecasing wall , tanks , and drill pipe into the mud .

• - Tubing string downhole .• - Establish circulation while reciprocating the tubing . Circulate the drilling mud

through available solids control equipment to remove large contaminants .• - Reduce the PV and YP to minimum acceptable levels .( See Fann70 prediction )

2 . 4 .3 Displacement Objectives : Hydraulic parameters will be adjusted after simulations with final rheology and tubingstring configuration . Spacer should cover a minimum of 200 m in the annulus at its widest diameter , and mustbe more viscous than the drilling mud . Chemical Washers , provide chemical cleaning action in combination with mechanicalscraping action , contain surfactants or solvents to remove inorganic contaminants .

Pumping Sequence No 1 and SAFETY -

A - Pump XP07 fluid pill - 8 m³ ( 0.77 SG) B - Displace mud by pumping a High Viscous sweep ( 25 m3 ) , using XC Polymer as aprimary viscosifier + 10 % of RX-03 Flocculant ( SG = 1.30 ) C - Pump Sea Water in the well

STOP ONCE the Sea water is return to the surface

SAFETY :

- At this Stage after the first bottom up with drill water a WELL OBSERVATION MUSTBE DONE .Duration 6 hours Note :During this time the Rig installation will be cleaned ,( clean up preparation logistic

, supply boat ) A close monitoring of volume pit ( Trip tank ) levels is required . - In case of any doubt on pit volume , flowing back etc… ,the situation must be evaluated . The Rig pump + the Dowell Unit must be ready to pump kill mud.

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Pumping Sequence No2 - SAFETY - A - Displace Sea water by pumping a High Viscous sweep ( 25 m3 or 157 bbl ) , usingviscosifier ( SG = 1.05 ) + 10 % of RX-03 B - Pump Chemical washers : “Final Clean up “ at maxi Flow rate ( 1200 /1500 l/min ) MFCT in closed Position ( allowing flow into liner ) B1 - Sea water + 6% of RX-16/1or RX-6BD Water wetting detergent ( 15/20 m³ ) B2 - Sea water + 3% of RX-03 (5 m3 ) Flocculant B3 - Sea Water pill ( 20 m3 ) B4 - Sea water + 6% of RX-16/1 or RX –6BD Water wetting detergent ( 30 m³ ) B5 - Sea water + 3% of RX-03 ( 30 m3 )

Operate MFCT to allow flow into 9 7/8” casing

C - Sea water until the well is clean

DO NOT STOP ONCE SPACERS ARE IN THE WELL .( segregation in the well )

SAFETY :

- At this Stage after the first bottom up with Sea water a WELL OBSERVATION MUSTBE DONE . A close monitoring of volume pit levels is required .{ HORNER Plot } - In case of any doubt on pit volume , flowing back etc… , the situation must be evaluated . The Rig pump + the Dowell Unit must be ready to pump kill mud.

After this flow check if levels are stable , the wellbore will be displaced with 1,00 SGdrill water treated with

! 1.4 kg/m³ BARASCAV L ( Ammonium Bisulphite )! + 1 kg/m³ of Biocide until clean return .! + 3 to 5 kgs/ m³ of Baracor 450 corrosion inhibitor .! + 5 kgs/ m³ of Sodium Bicarbonate ( galvanic coupling ).

3 . Inflow test :A special care should be taken during this Inflow Test ( see SHELL Experience onCommander well )Duration for the final Flow check . { HORNER Plot }

Temperature Effect ( see Enertech simulation )The cementing unit shall be used for the well killing

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4 . Chemicals Preparation :

Due to the logistic problems and the large volume involved during this operation a specialeffort must be done to reduce the Pollution to the sea .

4.1 Filtration Unit :POD unit with filters - Specification NTU = < 30 / 35 - Solids particules < 0.03%

5 . Recommended safety stock

Bulk material

- Dykerhoff G +S 50 tons- Baryte 250 tons .

Material in sacks or drums :

- Baracarb ( Fine & Medium ) 10 tons- CaCL2 brine 100 m³- Drilling Detergent 1600 liters ( Rig Wash )- LCM ( Fine/Medium ) 10 tons- Biocide 500 liters- Baracor 450 200 liters- Ammonium Bisulphite 500 Kgs- Sodium Bicarbonate 500 Kgs- All chemicals necessary to built 100 m³ of SBM .- Roamex Chemicals RX-03 - RX - 16/1 – 06 BD ( 100 % of back up volume )

Cement Additives for squeeze of cement .

6 . Balance Volume and Chemicals :

Hole Volume : 209 m³Annulus : 136.8 m³String : 49.26 m³

Active Mud and Kill Mud 300 m³ @ 2.15 SGIntermediate Mud or CaCl2/CaBr2 brine 150 m³ @ 1.60 SGDrill Water 750 m³ ( stock on board )

7 . Environment Rig cleanliness .

In order to keep the working environment on the rig clean and safe , it will be useful to usea rig detergent with a steam cleaner or high pressure water cleaner.Chemicals allowed to be discharged to the sea : Check MSDS for each chemicals .

All the contaminated spacer or water must be recovered in a dedicated pit and send to shore .

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8.3 Inflow Test – Horner Plot :

The horner plot technique can be used as a confirmation that we are in a steady state systemi.e. the inflow is only being caused by thermal expansion .

The use of the “ Horner Plot “ is based on a reservoir analysis build up technique where thepressure is plotted against horner time Ln ( T +dt ) / dt and the straight line portion of theplotted points indicates when we are in a steady state phase ( reservoir effects only ) with theextrapolation of the line tending towards initial reservoir pressure .

In our specific case we can treat the well as a reservoir and modify this technique such thatwe are plotting flowrate against horner time , with the straight line portion indicating asteady state condition . Added to this is that extrapolation of the line should trend to zero ,thus indicating that only thermal expansion is taking place within the well .Using this plot will give us a fairly quick indication that no abnormal effects are occuringand it will also give us a high degree of confidence in our inflow test .The flowing time T that should be used is :

The cumulative volume flowed during the final circulation

The average pump rate during the final circulation .

See Example attached .

inflow~3.xls

Well : 22/30c-G4 Liner lap inflow testProduction Casing displaced to 1.00 SG drill. water

Date : 30/12/98 Start time : 11:00 T= 1120 mins

Time (min) Flow (ml/min)Flow (USG/hr) Cum. Total (bbls) Ln((dT+T)/dT) Flow (l/min)20 7500 118.9 0.23589 4.0431 7.540 6666 105.7 0.44556 3.3673 6.760 6666 105.7 0.65522 2.9789 6.780 6000 95.1 0.84393 2.7081 6.0100 5000 79.3 1.00120 2.5014 5.0120 5000 79.3 1.15846 2.3354 5.0140 4615 73.2 1.30361 2.1972 4.6160 4615 73.2 1.44876 2.0794 4.6180 4286 67.9 1.58357 1.9772 4.3200 4286 67.9 1.71837 1.8871 4.3220 3750 59.4 1.83632 1.8068 3.8240 3750 59.4 1.95427 1.7346 3.8260 3333 52.8 2.05910 1.6692 3.3280 3333 52.8 2.16393 1.6094 3.3300 3333 52.8 2.26876 1.5546 3.3320 3158 50.1 2.36809 1.5041 3.2340 3158 50.1 2.46742 1.4572 3.2360 3000 47.6 2.56177 1.4137 3.0380 2875 45.6 2.65220 1.3730 2.9400 2727 43.2 2.73797 1.3350 2.7420 2500 39.6 2.81660 1.2993 2.5440 2400 38.0 2.89209 1.2657 2.4460 2308 36.6 2.96468 1.2340 2.3480 2222 35.2 3.03457 1.2040 2.2500 2143 34.0 3.10197 1.1756 2.1520 2069 32.8 3.16704 1.1486 2.1540 1818 28.8 3.22422 1.1230 1.8560 1935 30.7 3.28509 1.0986 1.9580 1818 28.8 3.34227 1.0754 1.8600 1875 29.7 3.40124 1.0531 1.9620 1818 28.8 3.45842 1.0319 1.8640 1818 28.8 3.51560 1.0116 1.8660 1765 28.0 3.57111 0.9921 1.8680 1667 26.4 3.62355 0.9734 1.7700 1538 24.4 3.67192 0.9555 1.5720 1538 24.4 3.72029 0.9383 1.5740 1463 23.2 3.76631 0.9217 1.5760 1463 23.2 3.81232 0.9057 1.5780 1429 22.7 3.85727 0.8903 1.4800 1429 22.7 3.90221 0.8755 1.4820 1333 21.1 3.94414 0.8611 1.3840 1333 21.1 3.98607 0.8473 1.3860 1224 19.4 4.02456 0.8339 1.2880 1250 19.8 4.06388 0.8210 1.3900 1224 19.4 4.10238 0.8085 1.2920 1200 19.0 4.14012 0.7963 1.2940 1177 18.7 4.17714 0.7846 1.2960 1154 18.3 4.21344 0.7732 1.2980 1132 17.9 4.24904 0.7621 1.11000 1091 17.3 4.28336 0.7514 1.11020 1071 17.0 4.31704 0.7410 1.11040 1071 17.0 4.35073 0.7309 1.11060 1000 15.9 4.38218 0.7211 1.01080 984 15.6 4.41313 0.7115 1.01100 968 15.3 4.44357 0.7022 1.01120 952 15.1 4.47352 0.6931 1.01140 938 14.9 4.50302 0.6843 0.91160 896 14.2 4.53120 0.6758 0.91180 896 14.2 4.55938 0.6674 0.91200 857 13.6 4.58634 0.6592 0.91220 896 14.2 4.61452 0.6513 0.91240 845 13.4 4.64110 0.6436 0.81260 800 12.7 4.66626 0.6360 0.81280 822 13.0 4.69211 0.6286 0.81300 789 12.5 4.71693 0.6214 0.81320 750 11.9 4.74052 0.6144 0.81340 698 11.1 4.76247 0.6075 0.71360 833 13.2 4.78867 0.6008 0.81380 741 11.7 4.81198 0.5942 0.71400 741 11.7 4.83528 0.5878 0.71420 625 9.9 4.85493 0.5815 0.61440 714 11.3 4.87740 0.5754 0.7

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elf exploration U.K.

Clean-up Summary Report F58bisVersion 2.0 8/96

Date :01/05/99 Clean-up Company : Field : ELGINDrilling contractor : Rig : Mud Company : Well number :

22/30 C - G5RATE MFCT VOLUMES NTU of RETURNS COMMENTS

16:20 16:30 2830 open Pit 1 Dump 25 25 Hi-vis Rx-03 10% Seawater N/A N/A N/A N/A16:30 16:35 3019 open Pit 2 Dump 15 40 RX-06BD 6% Seawater N/A N/A N/A N/A16:37 16:40 1490 closed Pit 7 Dump 5 45 Rx-03 3% Seawater N/A N/A N/A N/A16:40 16:53 1547-1604 closed Slug Dump 20 65 Seawater Seawater N/A N/A N/A N/A16:53 17:12 1604 closed Pit 2 Dump 29 94 RX-06BD 6% Seawater N/A N/A N/A N/A17:12 17:19 1547 closed Pit 7 Dump 11 105 Rx-03 3% Seawater N/A N/A N/A N/A17:21 17:30 3020 Open Pit 7 Dump 20 125 Rx-03 3% Seawater N/A N/A N/A N/A17:30 3020 Open Slug/Sea chest Dump Seawater Seawater N/A N/A N/A N/A

Open Slug/Sea chest Dump Seawater Hi-vis Rx-03 10% N/A N/A N/A Sample 1- 17:50Open Slug/Sea chest Dump Seawater Hi-vis Rx-03 10% N/A N/A N/A Sample 2- 17:53Open Slug/Sea chest Dump Seawater Hi-vis Rx-03 10% N/A N/A N/A Sample 3- 17:56Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 4- 17:59Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 5- 18:01Open Slug/Sea chest Dump Seawater Rx-03 3% N/A N/A N/A Sample 6 - 18:02Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 7 - 18:04Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 8 - 18:07Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 9 - 18:09Open Slug/Sea chest Dump Seawater RX-06BD 6% N/A N/A N/A Sample 10 - 18:11Open Slug/Sea chest Dump Seawater Rx-03 3% N/A N/A N/A Sample 11 - 18:14Open Slug/Sea chest Dump Seawater Rx-03 3% N/A N/A N/A Sample 12 - 18:18Open Slug/Sea chest Dump Seawater Rx-03 3% N/A N/A N/A Sample 13 - 18:23Open Slug/Sea chest Dump Seawater Rx-03 3% N/A N/A N/A Sample 14 - 18:26Open Slug/Sea chest Dump Seawater Rx-03/ Seawater N/A N/A N/A Sample 15 - 18:29Open Slug/Sea chest Dump Seawater Seawater N/A N/A N/A Sample 16 - 18:33Open Slug/Sea chest Dump Seawater Seawater 666 N/A N/A Sample 17 - 18:38Open Slug/Sea chest Dump Seawater Seawater 840 N/A <0.05 Sample 18 - 18:45Open Slug/Sea chest Dump Seawater Seawater 205 29 <0.02 Sample 19 - 18:55Open Slug/Sea chest Dump Seawater Seawater 42 10.5 <0.02 Sample 20 - 19:05Open Slug/Sea chest Dump Seawater Seawater 229 91.5 <0.02 Sample 21 - 19:15Open Slug/Sea chest Dump Seawater Seawater 223 48 <0.02 Sample 22 - 19:30Open Slug/Sea chest Dump Seawater Seawater 241 42 <0.02 Sample 23 - 19:45Open Slug/Sea chest Dump Seawater Seawater 108 38 <0.02 Sample 24 - 20:00Open Slug/Sea chest Dump Seawater Seawater 115 13.7 <0.02 Sample 25 - 20:15Open Slug/Sea chest Dump Seawater Seawater 123 34 <0.02 Sample 26 - 20:30Open Slug/Sea chest Dump Seawater Seawater 146 33 <0.02 Time 22:30Open Slug/Sea chest Dump Seawater Seawater 128 34.2 <0.02 Time 00:30Open Slug/Sea chest Dump Seawater Seawater 73.4 31 <0.02 Time 02:30Open Slug/Sea chest Dump Seawater Seawater 66.6 34.8 <0.02 Time 04:00

06:00 Open Pit 7/8/2/1 Dump Filtered drill water Seawater 83.8 47.4 <0.02 Time 06:3006:00 closed Pit 7/8/2/1 Dump Filtered drill water Seawater 91.3 39.4 <0.02 Time 07:00

closed Pit 7/8/2/1 Dump Filtered drill water Seawater 290 220 <0.02 Time 07:10Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 116 69 <0.02 Time 07:15Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 196 143 <0.02 Time 07:22Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 99.4 65 <0.02 Time 07:26Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 77.4 48.6 <0.02 Time 07:30Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 30.6 14 <0.02 Time 07:35Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 38.6 16 <0.02 Time 07:40

07:42 Open Pit 7/8/2/1 Dump Filtered drill waterFiltered drill water 29 15 <0.02 Time 07:42

Casing Size Casing Weight Lenght Eqpt. Description Base Fluid Volume Additives Density Rheology @ 50°C

9 7/8" 66.9 pptf 4,895 m Type m³ Type Concentration (SG) 600/300/200/100/6/3

7" 42.7 pptf 628 m Hi-vis 25 Rx-03 10% YP 48Seawater 42 RX-06BD 6%Seawater 6 Rx-03 3%

5,560 m

Geometry Volume (m³) Length9 7/8" 168 4,895

7" 13 628 m181 0

Comments / Job Summary

ELF supervisors : Phillipe Brossard - Fabian Lemesnager Mud Engineers: Stephen Cooper, Philip Leslie, Lee Campbell.

The clean-up operation was aided by detailed and thourogh pit and topsides cleaning. This allowed all pills to remain free of contaminants prior to pumping. All pills were pumped on the run and at high rates adding turbulent flow. Pipe rotation was only possible after the operation of the MFCT. Initial pills showed large amounts of solids which reduced in following samples. Sea water samples contained a large amount of rust which was removed with HCL.

roemex~1.xls,09/07/2000,13:05 Elf Fluids Group - Aberdeen

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Target NTU

Inhibited filtered fresh water returns.

Returns from surface lines

Sea water returns.

22/30c-G5

Sperry Sun Logging Systems

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Temperature Out

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8.4 Well Control – Pipe light scenario during completion of 22/30c-G4 with 1.00SGfluid :

The issue of Well Control with freshwater in the well was raised.It had made a quick review of theposition we have at the moment.It was suggested that based around this we can meet and discusswhether we need to make any further contingency plans (unable to strip in, unable to bullhead,access through the drillpipe with DISV and inside BOP, etc.).

Recommendations• The section covering Stripping, snubbing, migrating gas, bullheading and top kill (lubrication)

should be transferred from the old Well Control Manual (1993) to the Well Control Manualissued in June 1997 (the new manual does not contain this information). This section should bereviewed to ensure it is in line with procedures we would use if we had to perform any of theseoperations with water in the well in HPHT conditions.

• The results listed below should be included in the Completion Programme to make people awareof the limitations of stripping if we have a leak with water in the well.

Results / Conclusions• In the event of a gas influx the situation is very different to a kick with SBM in the hole because:

- An insignificant volume of gas will dissolve in the water- Water is 1.8 times less compressiblethan oil - the surface pressure build up will occur more quickly- The gas will migrate rapidly tosurface due to the low fluid viscosity (rapid increase in surface pressure as the bubble migrates-The coefficient of thermal expansion of water is 5 times greater than base oil which, withoutviscosity means the water is very sensitive to the thermal changes.

• Given the scenario:-The well is displaced to water-We have the highest formation pressure (2.15SG) giving a shut-in surface pressure of 650 bars-The drillstring is displaced to 2.15 SG mud We will not be able to strip into the well (using the 2ram method of passing tool joints) if the 5” drillstring is shallower than 2000m MD (upwardforces exceed downward forces - pipe-light (Refer to the graph on page 3).

• Given a pipe light situation with the drillstring partially in the well the upper portion of the wellcan be displaced to SBM..The advantage of this are:- It will allow limited gas percolating through the water to be taken into solution in the SBM

(assuming we can displace deep enough to be below the bubble point i.e.; deeper than1500m).

- It will reduce the surface pressure (this does not help us with the pipe light condition forstripping the pipe body as the pressure acting on the area at the base of the drill string remainsunchanged) Refer to the drawing below.The disadvantages are:

- A potential for fluid inversion with heavy fluid over light fluid- A potential for barite dropoutat the fluid interface

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Annular displacem ent to heavy m ud w ith the drill string partially in the w ell

Surface pressure reduced315 Bars 651 bars

Tool joint

Rams

Drillpipe

No change in pressure 2.15 SG Drilling Fluid (upward force on Drillpipe body OD)

with water or mud above this pointNet 44 MT upward force

3100m MD, 2975m TVD RT 943 bars

Depth

Water Gradient Water Gradient

5923m MD, 5776m TVD RT 566 bars 1217 barsPressure 2.15 SG EMW Formation pressure

22/30c-G 4 Pipe Light Condition(2.15 SG in string - 2.15 SG EM W Form P)

-150

-100

-50

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0 1000 2000 3000 4000 5000 6000

M D M

MT Net String For

Force on Pipe OD TonnesForce on Pipe TJ OD Tonnes

Minimum string depth to strip tool joint.With 1.00SG in annulus

Minimum string depth to strip tool joint.After disp ann to 2.15SG fluid

Minimum string depth to strip pipe body.

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In the graph above the negative Net string force indicates a pipe light condition

Well Control with Freshwater in the well

Our primary approach to this issue is to ensure there is no influx by:-

• Make-up the 10 3/4”, 9 7/8” and 7” casing connections using torque turn equipment with qualitycontrol review of the make-up.

• Review the quality of the 7” cementation and the cement bond log.• To have set and positively pressure tested a 7” liner top packer.• Ensure the well is stable with freshwater prior to pulling the displacement string. (To do this we

plan to underbalance the well in 2 stages on 22/30c-G4; firstly SBM at 1.60 SG and then tofreshwater. We will allow the well temperature profile to return to undisturbed (+/-24 hours)before pulling the displacement string).

Our second approach is to have a contingency plan prepared should an influx occur.

• The well can be circulated back to a kill weight fluid should the well fail during the initialdisplacement to underbalanced fluid (drillpipe on bottom).

• If the well flows while we are out of or partially out of the well we will strip in to bottom or asdeep as we can get. Should there be a pipe light situation we would not be able to strip furtherand have to stop with the well shut-in on the rams. This attached graph identifies the period inwhich we would be unable to strip into 22/30c-G4 if there is an influx with water in the well.

Calculation of forces The forces taken into account for this calculation are:" Pipe weight in air (5” drillpipe 19.5ppf nominal, 22.6ppf with tool joint)" Hydrostatic pressure of fluid inside the drill string acting on the pipe body ID cross sectional area" Weight of HWDP (40 joints 5” HWDP at 50ppf) - if they are available and can be picked up.# Hydrostatic pressure and shut-in well pressure acting on the cross sectional area of the pipe body

OD# Shut-in well pressure at surface acting on the tool joint cross sectional area (as the tool joint is

stripped through the BOP) This force is excluded when the tool joints are passed through theBOP by alternately opening and closing 2 rams and balancing the pressure.

# Friction while stripping through the BOP (Pipe friction through annular used is 5MT on pipebody and 14MT on tool joint - based on Franklin annular stripping data)

There are no safety margins taken into account in the calculations.

Sensitivity graphs on the next 2 pages

The following graphs are sensitivities assuming different formation pressures and fluid densitiesinside the drillpipe:

t

Volume 1





15

2.15SG - pressure from the overpressured shales in the transition zone

22/30c-G 4 P ipe Light C ondition(1.00 S G in string - 2.15 S G EM W Form P )

-150

-100

-50

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000

M D M

MT Net String For

Force on Pipe ODTonnes

Force on Pipe TJ ODTonnes

2.01 SG based on RFT data from the Fulmar reservoir

22/30c-G 4 P ipe Light C ondition

(2.15 S G in string - 2.01 S G EM W Form P )

-150

-100

-50

0

50

100

150

200

0 2000 4000 6000

M D M

MT Net String For



t

Volume 1





16

2.01 SG based on RFT data from the Fulmar reservoir

22/30c-G 4 P ipe Light C ondition(1.00 S G in string - 2.01 S G EM W Form P )

-150

-100

-50

0

50

100

150

200

0 1000 2000 3000 4000 5000 6000

M D M

MT Net String For



Elgin HT-HT Best Practice

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