SPE-54357-MS

Copyright 1999, Society of Petroleum Engineers Inc.

This paper was prepared for presentation at the 1999 SPE Asia Pacific Oil and GasConference and Exhibition held in Jakarta, Indonesia, 2022 April 1999.

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AbstractSelecting water/gas shut-off (WGSO) candidates with properunderstanding is a critical step which influences outcome ofany WGSO effort. Quite often an inexperienced engineer isperplexed by the task of having to find candidates forwater/gas shut-off applications, whereas he/she has little ideaas to where to start. He/she gets even more confused byselection criteria suggested by various authors, which aren'tvery clear.

In this paper a systematic approach for finding suitablecandidates for WGSO applications is presented. Severaltechniques of WGSO candidate pre-screening are discussed. Astep by step procedure which takes the engineer through aclear thinking process is suggested. WGSO candidatesselection is best treated as part of his/her routine wellboreutility study (yearly event). Starting point is to conduct a welland reservoir performance review for the entire field based onall the data in hand. A list of required basic data which arehelpful in this review is provided, as much of which aspossible should be collated prior to this candidate selectionexercise. Guidelines for further diagnosis to firm up WGSOcandidates is also provided. Outcome of this study is acomprehensive list of all potential remedial work, of whichWGSO is a subset. Having a complete picture of the well andreservoir performance helps an engineer understand reservoirfluid movement mechanism and therefore objectives of anyremedial work becomes very clear. Then the engineer canreview all products and services available in the market andcan choose the most appropriate solution. Without a properdiagnosis and clear understanding of reservoir fluid flowpattern, any attempted solution will only be a guesswork andsuccess rate will remain low.

IntroductionThere has been a lot of talk about various Water and Gas Shut-off (WGSO) technology in the oil industry. Service and oilcompanies R&D sectors continue to come up with newproducts and solutions claiming to offer better chances ofsuccess. Despite a lot of interest from the industry, theirapplication has not grown proportionately, thwarted byindustry-wide disappointing success rate. Oil companiescontinue to look for avenues to minimise water & gasproduction from oil wells while maintaining or enhancing oilproduction, in their pursuit of operating cost reduction.Engineers get instructions from management to look intoWGSO technology applications in order to reduce burden ofwater handling cost / reserves loss / reservoir energy loss. Theidea of being able to stop excessive water or gas productionfrom oil producing wells sounds very attractive, since theyclaim to be able to stop production of the unwanted phase andseek out oil only. Quite often a new engineer is perplexed bythe task of having to find candidates for water/gas shut-offapplications, whereas he/she has little idea as to where to start.He/she gets even more confused by selection criteriasuggested by various authors for various technology.

The concept of shutting unwanted gas or water from an oilproducer is nothing new and has been being applied sinceearly days of the industry. The only difference is, innovativesolutions to perform the job in smarter ways keep on comingin. However, not all the innovative solutions bring the desiredresults as claimed because of various reasons. Some of thetechnology are not proven1 and implementation of others2,3 aredifficult/expensive. From an engineers point of view, oneshould look at defining and solving a problem in hand ratherthan trying to apply a given technology i.e. the problem butnot the solution should be the driver.

Literature ReviewA numerous papers have been published on water and gas shutoff (WGSO) case studies using various chemicals, especiallypolymer gels. Some of them propose selection criteria toidentify potential candidates for the respective solutionoption.4,5,6,7 However, none of them talk about how theproblem in hand was defined, which is a critical step thatinfluences the outcome of any water or gas shut-offapplications. The current literature is quite poor in treating

SPE 54357

Water/Gas Shut-off Candidates SelectionA.H. Kabir, SPE M.A. Bakar, SPE, M.A. Salim, SPE, M. Othman, SPE and A. Yunos, SPE, Petronas Carigali Sdn. Bhd.

2 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

reservoir engineering aspect of problem wells (excessivewater/gas producer) identification. Chan8 described WaterControl Diagnostics Plots technique which can be helpful inidentifying WGSO candidates. Wu et.al.9 described an expertsystem which helps engineers come up with probability ofvarious water production mechanism. Hardy et.al.10 provided alist of reservoir, production and completion information thathelp determine water production mechanism. However,description of a systematic approach for WGSO candidatesselection is absent from the literature. For a novicesurveillance or production engineer this would help him/herdefine the problem clearly and he/she then could look for asuitable solution for the problem type in hand which isadequately addressed in the literature.

Moreover, in a real production environment, textbook typesymptoms for diagnosing a WGSO problem does not happenvery often. That is because, in theoretical study we cantmodel all the factors / phenomena that dictate the productionperformance of a well and sometimes a combination ofvarious factors manifest as hybrid symptoms. Decipheringthese require some thorough analysis in order to understandthe root cause(s).

Candidates Selection FundamentalsGood (or associated) water/gas can be defined as theamount of water/gas that must be produced together with theoil in order to produce the oil with the existing completionconfiguration. Bad (or harmful) water/gas can be defined asthe water /gas which is produced in excess to that requiredfor the production of hydrocarbon i.e. abnormal amount ofwater/gas. Some examples of good and bad water/gasare:

a) coning / cusping (good or bad)b) reservoir channelling (bad)

- high permeability streak (bad)- fissures, fractures, faults, vugs etc (bad)- hydraulic fractures grown out of zone (bad)- injector-producer communication through high

permeability intervals (bad)c) fingering (bad)d) behind pipe channelling (bad)e) depleting reservoir (good)

Having defined Bad and Good water/gas, delineationbetween good vs. bad water/gas could be quite difficult attimes. A good example would be coning. Coning could beboth good and bad based on the economics of any potentialconing control measure. In conventional completion (asopposed to simultaneous oil and water production for coningcontrol as in Downhole Water Loop2) reliable ways of coningcontrol are draw-down reduction (via rate control or PIincrease) and maintaining enough clearance from theOWC/GOC. Sometimes in order to produce a well aboveeconomic rate leaves one with no choice but to accept coningcondition.

The following conditions must be fulfilled before one looksinto potential solution options:

1) There is a well which produces excessive water or gaswhich is abnormal or bad.2) Fluid flow pattern in the reservoir and into the wellboreis understood with reasonable confidence.Then only one should scrutinise the solution options based

on their merits/de-merits.Fluid movement (flow path) visualisation is the most

challenging part of WGSO candidate selection. Withoutproper understanding of the fluid movement mechanism andthe entry of the unwanted phase (water or gas) into theperforations, chances of stemming any such flow is remote.

Integrating WGSO Diagnosis Work with RoutineWellbore Utility StudyIt is recommended that surveillance engineers handle WGSOcandidate selection as a part of their routine wellbore utilitystudy which will make his/her job simpler. In every E&Pcompany engineers review their well/reservoir performance atleast once a year and subsequently plan their rate enhancement/ remedial work. This wellbore utility study cycle is the besttime to start identifying problem water/gas producers andcontinue the work thereafter.

As much of the following data as possible need to be puttogether before the engineer embarks on such a study:

- production history- well history (workover, perforation etc)- wellbore schematics- well logs (open hole and cased hole)- reservoir and fluid properties- core reports / petrophysical data- depositional environment / geology- fluid contact (OWC / GOC) movement and pressure

history- structural map / cross-sections- stick diagram showing relative depth of perforations by

reservoir- drive mechanism / depletion strategy- reserves information- simulation results, if any

Water/Gas Shut-off Diagnosis StepsDiagnosis of an excessive water or gas production problem isbest done in a step by step, modular fashion. Easier and lessexpensive investigation i.e. pre-screening is done at the earlierstage in order to understand fluid movement mechanism in thereservoir and into the well-bore. Further diagnosis work iswarranted only when the easier and simpler work prove to beinadequate to provide an answer with reasonable degree ofconfidence. Fig.1 summarises WGSO candidate selectionprocess in a flow chart format which is summarised below.This proposed work flow is further illustrated through somecase studies described later.

SPE 54357 WATER/GAS SHUT-OFF CANDIDATES SELECTION 3

Pre-screening1) Well & reservoir production history analysis (plotting)2) Correlation of any production performance change withwell workover, events, production condition changes (chokes,separator pressure etc), reservoir intervention (onset or changein IOR/EOR process) or drive mechanism changes (eg.pressure decline below bubble point) etc.3) Water Control Diagnostic Plots8 analysis4) Well and reservoir information review (wellboreschematics, well logs, reservoir and fluid properties, geology,core reports etc)5) Reservoir OWC/GOC history and relative well position(depth and space) data reconciliation with well performance

- WC/GOR scattergram analysis- stick diagram of the wells in the same reservoir- stratigraphic cross correlation of neighbouring wells- fluid contact movement data analysis

6) Reserves analysis:- reserves estimation using various methods (decline,

volumetric, simulation) and reconciliation- relative drainage area comparison assuming known / best

estimate reservoir parameters i.e. Bubble Map analysis7) Reservoir simulation results analysis8) Easy diagnosis work (production and multirate test, tubingintegrity test, well configuration check etc)

If the pre-screening work succeeds in diagnosing theproblem, one can run simple economics to exclude obviouslyuneconomic candidates at this stage

Further Diagnosis1) Fluid contact logs (e.g. Pulsed Neutron Capture tools,

Gamma Ray Spectroscopy (saturation ) Tools etc.)2) Water movement detection logs (eg. radioactive surveys

like Water Flow Log, Hydrolog etc.)3) Production logging combination tools (temperature /

spinner / capacitance etc)4) Cement bond log5) Noise logs6) Pressure build-up tests7) Tracer testing8) Downhole video camera9) 4-D seismic result

Opportunities InventoryAt the end of the diagnosis work the engineer will come upwith a clear picture of reservoir fluid movement pattern and itsflow into the wellbore. Now this well will be added to thewellbore opportunities list which is further refined as theavailable solution options and their viability are considered.

Candidates Selection PhilosophyMake use of data in hand first before starting to invest inexpensive diagnosis work. Pre-screening exercise helps onenarrow down potential candidates by making use of the data inhand. As one gradually narrows down his/her candidate pool,

he/she proceeds with further diagnosis which demands moreefforts and resources.

Use performance plots , Water Control Diagnostic Plotsetc. as probable indicative tools which sometimes guide onein the right direction. No single tool (except for the hard data)is to be taken as the diagnosis tool; they should rather betreated as subset of a suite of tools (described above) whichshould be reviewed and reconciled. A close attention isrequired to understand the reservoir fluid movement patternand its flow into the wellbore. For example, a well which hasbeen shut-in for a long time may show a sudden jump in WCor GOR in the performance plot if it was plotted against Np orCumulative Producing Days, which is indicative ofchannelling8,. This false alarm may be due to production fromthe neighbouring wells while the well in question was shut-inand fluid contact may have moved in the mean time.Example1 (below) illustrates one such case.

Case Studies of Some WGSO Candidates SelectionExamples of some WGSO candidate selection are describedbelow. Three wells from Tinggi field have been chosen forillustration.

Field HistoryTinggi field is part of PM-9 block, located in the south-eastern part of the Malay Basin, approximately 280 kilometresoffshore east of Kerteh, Terengganu, Malaysia (Fig.2). Thisfield was developed during August 1982 to March 1984.Tinggi structure is a small east-west trending anticline (4.5 kmx 1.5 km at J reservoirs OOWC) with a vertical relief of100 meters. J, the major group of reservoirs, are early Mioceneage sandstone accumulation deposited in a shallow marineenvironment. These reservoirs produce under a combination ofnatural water drive and gas re-injection at the crest of thesmall cap present. About 91% of their UR (101.1 MMSTB)has been depleted with current WC of 85% and GOR 1200scf/STB.

Example 1 (Well Tinggi A-19)Tinggi A-19 was completed in J15/16 reservoir in 1983. WORand WOR of its historical production data (Fig.3) shows apositive slope after about 2500 production days. This at thefirst instance makes one suspect water channelling behaviourdescribed by Chan8. A closer look at the normal productionhistory plot (Fig.4) reveals that the well was shut inintermittently during 1992-1994 period and those positivejumps in WOR and WOR are caused by OWC rise due toneighbouring wells production during A-19s shut-in periods.Another close look at the WOR/WOR plot shows that WORalso has negative slopes segments alternating with positiveones. GOR and WC fluctuation in later years can be related toseparator pressure fluctuation due to periods of low pressuremode operation and wellhead choke changes. One exception isDecember 96s WC and GOR data, which appear to be

4 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

erroneous and can be related to use of an unvalidated testduring production allocation.

Production history plots vs. Np (Fig.5) also show WCjumps like WOR/WOR plot, which can mislead one tosuspect channelling behaviour, if not correlated with wellhistory and production condition changes. After a detailedreview of the well logs, completion configuration, volumetricreserves estimate, production performance correlation withnearby wells etc. it was concluded that this well is normal andit is not producing any bad water or gas.

Example 2 (Well Tinggi A-12)As it can be seen from the production history of the well(Figs.6,7), WC took a sudden jump in late 1990 after it wasput back on line following a 5-month shut-in period (for gaslift valve installation). This triggers the question of anypotential water channelling problem. GOR drop in 1989 ismost likely due to gas cone subsidence during shut-in period.The 1990 GOR spike could be due to very low oil volume andminor gas measurement error. GOR values have been quitelow (max. 1500 scf/STB, Rsi 685 scf/STB) and no furtherinvestigation was warranted. However, water productionbecame a problem all on a sudden. The well tested up to99.6% WC in subsequent short flowing periods in 1993, 1997and 1998 (not included in the production history plot) andtherefore has been kept shut-in. The WOR/WOR plot (Fig.8)seems to show a positive slope, however a closer look showsthat these values were actually fluctuating, however showing asudden jump at the end, indicative of channelling.8 In thiscase, please note that WOR/WOR plot reveals no extrainformation other than what is evident from normal productionhistory plots.

Subsequently well history, logs (Fig.9) and completionschematic (Fig.10) were checked. The well was completed inJ15/16 and J17 sand in March 1983 and was producedcommingled by two sets of perforation intervals, 4.0 and 5.0 mrespectively. Gamma ray readings (Fig.9) suggests that J15/16reservoir is of much poorer quality compared to lower J17reservoir. A significant shale streak exists between these twozones. Initial WC increase of the well till 1990 looks gradualand normal given that the original OWC was about 14.4 mTVD below lower perforation interval. The sudden increase ofWC in late 1990 could be due to any kind of channelling orOWC movement during 7 months shut-in period. However,reservoir wide WC performance plot does not suggest such adrastic increase of water level within that 7 months ofproduction.

Further Analysis and Diagnosis Needs. The followinganalysis and diagnosis could be carried out in order tounderstand fluid movement mechanism in the reservoir andinto the wellbore:

a) Well Scattergram (WC/Np) of the reservoirsb) Bubble Map of the J15/16/17 reservoirc) multi-rate well test to test coning effect

d) run Production Logging Combination Tool to seecontributions (and fluid type) from both the zones and anyother source of water inflow.

e) run water movement detection logItems (a), (b) and (c) are easy & inexpensive to do and

therefore were carried out immediately. J15/16 Scattergram(Fig.11) is revealing in the sense that it indicates A-12 WC tobe much higher than any of the neighbouring wells in the samereservoir. J17 Scattergram (Fig.12) indicates that A-12performance is in line with other J17 completions. Multiratewell test was conducted by varying lift gas volume, howeverall the tests recorded WC above 99%.

From the above easy analysis and diagnostic work it seemsthat A-12 performance match closely with others from J17 butnot of those from J15/16. Also given the rock quality contrastbetween J15/16 and J17 (Fig.9) raises the question whetherJ15/16 is contributing at all. Therefore it was decided toconduct Production Logging to see contributions from both thecommingled zones. The result of the production log ispresented in Fig. 13. The Spinner and Capacitance curveclearly indicate that majority of the flow was coming from J17with minor hydrocarbon contribution from J15/16. Based onthis result , it was concluded that J15/16 sand is notcontributing to A-12s production which is supported by allearlier analysis and further expensive diagnostic work wasdeemed unnecessary. It was, therefore, decided to squeeze thebottom perforations with cement slurry and reperforate theJ15/16 interval. The job will be carried out in April 1999.

Example 3 (Well Tinggi A-2)Tinggi A-2 was completed in the J17 sand in October 1982.Fig.14 shows a simple well schematic. Production history(Figs.15,16) shows that WC started increasing in 1991 andreached 50% in 1996. In early 1997 WC took a sudden jumpto 90% after a short SI period. This arouses curiosity as towhy and how WC made such a jump. Water ControlDiagnostic Plot (Fig.17) suggests coning behaviour in theearly life with one sudden jump which corresponds to early97. Again quick examination of composite log (Fig.18)suggests coning is unlikely to be the water productionmechanism since J17 is a coarsening upward sequence withshort limestone streaks in the lower part. The vertical distancefrom the OOWC to the bottom of the perforation interval is24.7m (81ft). If coning was the water production mechanism itwould not take water 8 years to break through in this qualityreservoir (J17 average permeability 300mD, oil gravity 470

API, bottom-hole temperature is 205 oF). Unfortunately WaterControl Diagnostic Plot does not help in diagnosing theproblem. J17 Well Scattergram (Fig.12) WC distributionsuggests that 90% water is consistent with its relative positionin the structure. A-2 perforation intervals relative verticalposition can be visualised from a stick diagram of the wells(Fig.19), which supports the earlier statement. Also Np of thiswell (7.6 MMSTB) is the highest in this sand, suggesting thatdrainage area covered is relatively large and chances of by-passed oil are low which is supported by the Bubble Map of

SPE 54357 WATER/GAS SHUT-OFF CANDIDATES SELECTION 5

J17 sand (Fig.20). A quick review of the stratigraphic crosscorrelation of the neighbouring wells (Fig.21) supports theabove analysis. All neighbouring completions in J17 havebeen watered out . However, some shaley streaks at the lowerpart of J17 is evident from the Gamma Ray curves. Theserelatively lower permeability streaks have the potential to holdup some unswept oil.

Further Analysis and Diagnosis Needs. Based on theabove analysis it was decided to conduct the following furtherdiagnosis work :

a) multi-rate well test to confirm that coning was not anwater production mechanism

b) run Gamma Ray Spectroscopy Tool to see OWC andany unswept oil patches.

Fig.22 shows result of multirate well tests which showsWC almost constant indicating no coning. Saturation log(GST) result (Fig.23) suggests OWC at 1316.1 mTVDSS or5657.7 ftMD which is at the lower part of the perforationinterval. Moreover no unswept hydrocarbon zones belowcurrent OWC is present. From these findings it is clear thatwater is being produced normally from the lower part of theperforations. Given the coarsening upward sequence of J17sand, lower part of the perforations would be relatively lessprolific and benefit of any gel squeeze at the lower part willnot be very attractive. Moreover, since there is no permeabilitybarrier in J17 itself (lower permeability shaley streaks are notbarriers, since they did not hold up oil), water will veryquickly find its way to the perforations. Also, squeezingsealant gel to the lower part of perforations by dual pumpingwas assessed as difficult to implement (risky). Therefore, itwas decided to let this well produce till depletion at its currentmode (normal).

Conclusionsa) Accurate diagnosis of excessive water/gas production

i.e. understanding reservoir fluid flow pattern (flow pathvisualisation) is a prerequisite for any water or gas shut-offapplication.

b) Treat water/gas shut-off work as part of routinewellbore utility study and production enhancement efforts.This makes engineers task easier. WGSO work should beproblem driven and any push by management to apply newunproven technology in a hurry must not be treated as alicense to skip diagnosis work, if one wants to stand anychance of success.

c) A systematic approach to diagnose WGSO problem hasbeen developed. This proposes that the engineer uses thesimpler data in hand first, before plunging into expensivediagnostic work and he/she progressively narrows down toroot cause of water/gas production, be it normal or abnormal.

d) Avoid selecting candidates for WGSO work solelybased on production history or diagnostic plots. Need tointegrate these with well history, log data, geologicalinformation, production and stratigraphic correlation withneighbouring wells, fluid contact data etc.

AcknowledgementWe would like to thank Petroliam Nasianal Berhad(PETRONAS) and Petronas Carigali Sdn Bhd (PCSB)management staff for their support in carrying out theinvestigation work and for their permission to publish thispaper. Our special thanks to Hj. Awis Ahmad (SeniorManager, PCSB) for his encouragement and support.

Nomenclature

bbl/d= barrel/dayCD= calendar dayEOR= enhanced oil recoveryGOC= gas oil contactGOR= gas oil ratio [scf/STB]GST= Gamma Ray Spectroscopy ToolIOR= improved oil recoveryKL= kilo litrekm3/d= thousand meter cube per dayM= thousandMD= measured depthmD= milli DarcyMM= millionNp= cumulative oil production [MMSTB]OOWC= original oil water contactOWC= oil water contactPLCT= production logging combination toolsQo= oil production rate [bbl/day]scf= standard cubic feetSTB= stock tank barrelTVDSS= true vertical depth, sub-seaUR= ultimate recovery [MMSTB]WC= water cutWCDP= water control diagnostic plotsWGSO= water/gas shut-offWOR= water oil ratioWSO= water shut-off

References1. Stavland, A., Ekrann, S., Hettervik, K.O, Jakobsen, S.R.,

Schmidt, T. and Schilling, B.: Disproportionate PermeabilityReduction is Not a Panacea, paper SPE 50983, SPE ReservoirEvaluation and Engineering, August 1998.

2. Wojtanowicz, A.K. and Xu, H.: A New In-Situ Method toMinimise Oilwell Production Watercut Using Downhole WaterLoop, paper CIM 92-13, Proc. 43rd Annual Technical Meeting ofthe Petroleum Society of CIM, Calgary, 1992.

3. Wojtanowicz, A.K., Xu, H.and Bassiouni, Z.: Oilwell ConingControl Using Dual Completion With Tailpipe Water Sink.Oklahoma, paper SPE 21654, Proc. SPE Productions Symposium,1991.

4. Bakar, J.A., Henry, T.B. and Mokhtar, S.M.: SamarangWater Shut-off Using Pfizer Floperm 500, paper presented at theWater Abatement Technology Workshop held in Langkawi, Kedah,Malaysia, 11-12 September 1995.

5. Gandawidjaja, P and Indra H.P.: Acrylamide-copolymer Gelfor Profile Modificaion: A Case Study in Central Sumatra Basin,Indonesia, paper SPE/DOE 35384 presented at the 1996 SPE/DOETenth Symposium on IOR held in Tulsa OK, 21-24 April 1996.

6 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

6. Barge, D.L., Kalfoglou, G. and Wibowo, B.C.: Case History:Water Control Treatment in the Minas Field, Central Sumatra,Indonesia, paper presented at the Twenty Third Annual Convention,Indonesian Petroleum Association, October 1994.

7. Sanders, G.S., Chambers, M.J. and Lane, R.H.: SuccessfulGas Shut-off With Polymer Gel Using Temperature Modelling andSelective Placement in the Prudhoe Bay Field, paper SPE 28502presented at the SPE 69th ATC&E held in New Orleans, LA, USA,25-28 September 1994.

8. Chan, K.S. : Water Control Diagnostic Plots, paper SPE30775 presented at the SPE Annual Technical Conference andExhibition, Dallas, Texas, October 22-25,1995.

9. Wu, F.H., Chiu, T.J., Dalrymple, D., Dahi, J. and Rahimi,A.B.: Development of an Expert System for Water Control

Applications, paper SPE 27552 presented at the PetroleumComputer Conference held in Aberdeen, U.K., 15-17 March 1994.

10. Hardy, M., Batenburg, D.V. and Botermans, W.:Improvements in the Design of Water Shut-off Treatments, paperSPE 38562 presented at the SPE Offshore European Conference heldin Aberdin, Scotland, 9-12 September, 1997.

SI Metric Conversion Factors

bbl x 1.589 873 E-01 = m3

ft x 3.048 E-01 = moF (oF-32)/1.8 = oCoAPI (141.5/(131.5+oAPI)) = g/cm3

mD x 9.869 233 E-04 = mm2

Fig. 1-Water/gas shut off candidates selection process.

REVIEW WELL PERFORMANCE

WC/GOR PERFORMANCE ANOMALY

HIGH WC/GOR?

WELL/RESERVOIR PERFORMANCE REVIEW

Y

EASY DIAGNOSIS WORK (WELL TEST/ WIRELINE CHECK)

ROUGH ECONOMICS TO JUSTIFY FURTHER INVESTIGATION

JUSTIFIED?

FURTHER DIAGNOSIS WORK (DETERMINE CONTACTS, FLOW PATHS, SOURCE OF WTAER/GAS)

BASKET OF WGSO CANDIDATE WELLS

SELECT TECHNOLOGY AND IMPLEMENT

N

STOP

N

Pre

-scr

een

ing

Fu

rth

er

Dia

gn

osi

s

Prepare list of candidates with complete documentation of source of water/gas and mode of production)

Production history / well history :Analyse production performance (plots)Try to correlate events with performance changesWater/Gas Control Diagnostic Plots

Well/Reservoir Performance Review :wellbore schematics & logsreservoir & fluid propertiesOWC/GOC & Pressure historystructural map / stick diagramstratigraphic cross-correlation core reports / petrophysical datareserves analysis

Easy diagnosis :well test / multirate flow testwell configuration, integrity etc. check using wireline

Preliminary Reserves EstimateRun quick economics

Further diagnosis :Contact/ Saturation Logs, PLCT, Water Movement Log, Video Camera, Tracer Test etc.

Do

cum

enta

tio

n/

Rec

om

men

dat

ion

SPE 54357 WATER/GAS SHUT-OFF CANDIDATES SELECTION 7

Fig. 2-Tinggi field location.

Fig. 3-Tinggi A-19 water control diagnostic plot. Fig. 5-Tinggi A-19 production history versus cumulative Production.

Fig. 4-Tinggi A-19 production history versus time. Fig. 6-Tinggi A-12 (J-17 reservoir) production history versus time.

x

xx x

xxx

x

x

x

xx x

x

xxx x

xx

x xxxxxx

GELIGA

LEDANG

SELIGI AND PINANG

PINANG KACAMARMAR PULAI

BEKOK

KEPONGTIONG

MANIK

BERLIAN

BERANTAI

INTAN

IRONG BARATIRONG TAPIS

TABUGUNTONG

PALAS

PERMATA

TINGGI FIELD

PM-9 Block

South Chine Sea

East Peninsular Malaysia

Kerteh

8 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

Fig. 7-Tinggi A-12 (J-17 reservoir) production history versuscumulative production.

Fig. 8-Tinggi A-12 (J-17 reservoir) water control diagnostic Fig. 9-Tinggi A-12 completion log. The original field OWC wasplot. at 1338.1 mTVDSS.

Fig. 10-Tinggi A-12 wellbore schematic. The well was completed commingled in J-15/16 and J-17 which was separated by shale.

x

x xx

x xx

xxx

xxxx

x

xxxxx

x xxx x x

xx

x

FIELD OWC1338.1 mTVDSS

J-15/16

J-17

TVDSS1307.0 m

1310.9 m

1318.9 m

1322.9 m

SHALESHALE

SPE 54357 WATER/GAS SHUT-OFF CANDIDATES SELECTION 9

Fig. 11-J-15/16 reservoir well scattergram showing watercut distribution.

Fig. 12-J-17 reservoir well scattergram showing cumulative Fig. 13-Tinggi A-12 PLT log. It shows major flow from the J-17production and water cut distribution. Reservoir and no apparent flow from the J-15/16 reservoir.

Fig. 14-Tinggi A-02 wellbore schematic.

J-17

1308.5 m TVDSS

1318.3 m

OOWC -1338.1 m TVDSS

A-19(69%)A-29

(68%)A-9(50%)

A-16(40%)

A-31(35%)

A-28(69%) A-24

(98%)A-17(80%)

A-25(40%)

A-21(100%)

A-11

A-4

A-12(98%)

A-10 A-2A-18(95%)

A-15U (GI/GP)A-20U (GI)

OGOC -1283.2 m TVDSS

Description :Well NameWC - status as at 1.1.99

Legend :Penetrated & completedPenetrated but not completed

OOWC -1338.1 m TVDSS

LOSS OF PERMEABILITYFOR J-17 sst.

A-9(1.9,40%)

A-16(1.0,80%)

A-21(0.1,100%)

A-11(0.5,98%)

A-4

(0.4,50%)

A-12(3.5,98%) A-10

(0,100%)

A-2(7.6,90%)

A-18 (0.4,100%)

A-20U (GI)

OGOC -1283 m TVDSSA-13

(0.5,95%)

Description :Well NameNp (MMstb), WCstatus as at 1.1.99

10 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

Fig. 15-Tinggi A-02 production history versus time.

Fig. 16-Tinggi A-02 production history versus cumulative Fig. 18-Tinggi A-02 completion log.production.

Fig. 17-Tinggi A-02 water control diagnostic plot. Fig. 19-Stick diagram of J-15/16 and J-17 wells.

x

x x

xx

xx

x

xx x

xx

xx

xxxx

x

x xx

x x

xx x

x xx

xxxx

xx

x

x

x

A-16 A-09 A-04 A-12 A-10 A-02 A-18 A-11 A-21

1,340

1,320

1,300

1,280

1,260

DE

PT

H (

m-T

VD

SS

)

OOWC

CURRENT OWC@1316 mTVDss

J-15/16

J-17

80% 100%98%95%90%100%98%50%50%WC

OGOC

CURRENT GOC @ 1277 mTVDSS

PERFORATION INTERVAL

SPE 54357 WATER/GAS SHUT-OFF CANDIDATES SELECTION 11

Fig. 20-J-17 reservoir bubble map showing hypothetical drainage area.

Fig. 21-Stratigraphic cross correlation of J-17 completion (Tinggi A-02 and nearby wells).

TGA-12 TGA-10 TGA-02 TGA-11 TGA-18

98%1318.9

100%1303.0

90%1308.5

98%1302.5

100%1310.0

WATER CUTTOP (mTVDSS)

NOTE : Depth scale in MD, aligned at original OWC. TOP = Top of J-17 perforations.

ORIGINAL OWC @ 1338.1 mTVDSS

12 A.H. KABIR M.A. BAKAR, M.A. SALIM, M. OTHMAN AND A. YUNOS SPE 54357

Fig. 22-Tinggi A-02 multirate test result.

Fig. 23-Tinggi A-02 Gamma Ray Spectroscopy Tool (GST) log result.

Test 1 Test 2 Test 3 Test 4

TEST NUMBER

3

4

5

6

7

8

Gas

lift

(km

3/d

)

0

10

20

30

40

50

60

70

80

90

100

Wat

ercu

t (%

)

gaslift rate

water cut

perf

orat

ion

inte

rval