Guidelines for the Selection of a Waterflood Deoxygenation …petrowatertech.com/wp-content/uploads/2015/08/Deuel... · · 2015-08-24of a Waterflood Deoxygenation Strategy C. Deuel

Shell Exploration & Production

2/12

/200

7Fi

le T

itle

Cop

yrig

ht: S

hell

Expl

orat

ion

& P

rodu

ctio

n Ltd

.

Guidelines for the Selectionof a Waterflood

Deoxygenation Strategy

C. DeuelShell EPT-ProjectsHouston, TX

17th Annual Produced Water SeminarHilton Houston NASAClear Lake, TX

ThursdayJanuary 18, 2007

J. Walsh, PhDSEPCoNew Orleans, LA


Deuel, Walsh: Deoxygenation Guidance Slide No. 2

Types of Minox de-oxygenation systemsRecommended Strategy for Deepwater Waterflood Deoxygenation:

• Design for full chemical oxygen scavenger as a base case

– Provide sufficient residence time for scavenger reaction

• may require a retention vessel

• required dose depends on temperature, mixing and scavenger concentration

• w/o sulfate membranes: use catalyzed scavenger & provide 3 minutes to react

• w/ sulfate membranes, can't use catalyst so provide 5 minutes to react

– Select appropriate metallurgy for poor scavenging & MIC control

– Provide sufficient storage for 10 days

• Add mechanical deoxygenation in order to reduce OPEX

– Required dose for chemical may be excessive in cold water

– For Basis of Economics:

• use historical / real uptime data (see below)

• use real operating costs including Minox catalyst and other chemical costs



SeaJect - Extensive field trials

– Developed initially by Norsk Process Inc. in 1980's

• Initial funding / interest by Conoco

– 1990 Shell testing on shore

– 1990 One week pilot field test on Cognac

– 1992/1993 One year Bullwinkle field trial in parallel train

• review report - many problems, excessive downtime

– 1994 - 2001 Shell Ram-Powell waterflood - SeaJect on-line

• many problems, excessive downtime

• relying on chemical oxygen scavenger

• extensive well tubing corrosion

– 1998 Axsia Serck Baker acquires SeaJect

– 2001 Shell selects SeaJect for Bonga

– 2001 Shell decommissions SeaJect on Ram-Powell

Historical Involvement in Compact Deoxygenation:



2001 / 2002 Pivotal Years:

– SeaJect selected for Bonga & GA approved for construction

• But operations raise strong objections

– Mars WF approved assuming compact deoxygenation

• GA, weight & space constrained

– Shell acquires Enterprise, inc Bijupira-Salema

• Minox selected by Modec / Alliance Engineering, designed by Minox

– Shell & BP (Mars partner) share their experience:

• BP initial good experience with Minox

• Minox selected for several more BP waterfloods

• Not much industry experience available regarding Minox

Shell selects Minox for both Mars and Bonga

Historical Involvement in Compact Deoxygenation:



MeOHGas Blower

WF DeOx System – Common to all 3 DW WF:

Oxygen scavenger

Instrument Air

Gas/Gas HEx

Electric HeaterCatalystBed

1st StageSeparator

2nd StageSeparator

!Overall nitrogen / seawater flow is counter-current

!Local nitrogen / seawater flow is co-current• nitrogen / seawater mixing in static mixers

!High efficiency from:• small bubble size (high surface area, short gas diffusion length)• 2-stage counter-current process



Shell Brazil Bijupira-Salema water injection performance

Wat

er in

ject

ion

rate

(cub

es /

day)

Bypass Minox –Using full chemical scavenger insteadDramatic Uptime Improvement

Void

age

Rep

lace

men

t(c

ubes

/ da

y)



WF2 Operating Experience

Minox: 40 % average downtime

BWPD

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

Mar

-04

Apr

-04

May

-04

Jun-

04

Jul-0

4

Aug

-04

Sep

-04

Oct

-04

Nov

-04

Dec

-04

Jan-

05

Feb-

05

Mar

-05

Apr

-05

May

-05

Jun-

05

Jul-0

5

Aug

-05

Sep

-05

Oct

-05

Flexjoint

targets

HP pump

HP pump

HP pumpKatrina

BWPD

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

Mar

-04

Apr

-04

May

-04

Jun-

04

Jul-0

4

Aug

-04

Sep

-04

Oct

-04

Nov

-04

Dec

-04

Jan-

05

Feb-

05

Mar

-05

Apr

-05

May

-05

Jun-

05

Jul-0

5

Aug

-05

Sep

-05

Oct

-05

Flexjoint

targets

HP pump

HP pump

HP pumpKatrina

Minox downtime

Mars topsides performance



Project Company Mark DateInstalled

CapacitykBWPD

WorkingEffectively Comments

Snorre Saga 1991 375

Foinaven BP Mark 1 1995 165 YMinox unit very successful here - single stage, using the catalyst reactor. Static mixer & stripping tower contactor / separator.

Schiehallion BP Mark 1 1996 280 N76% injection against target - single stage, using the catalyst reactor. Static mixer & stripping tower contactor / separator.

Vigdis (Snorre) Saga 1996 136Masa Petronas 1998 25Siri Statoil 1998 81.5Statfjord Statoil 1998 790 Conversion of fuel gas stripping towerGabon Marathon 1999 45 - Not installedPogo 1 (Thailand) Chevron 1999 20 N Not operatingPogo 3 (Thailand) Chevron 1999 40 N Not operatingGlitne (FPSO) Statoil PGS 2000 65Pogo 2 (Thailand) Chevron 2000 20 N Not operatingValHall BP Two stage 2000 220 NHalfdan Maersk 2001 220 Y Fixed by NATCoHeidrun Statoil 2001 200

Bijupira Salema Shell Mark 3 2002 100 N Minox currently by-passed. Relying on oxygen scavenger.

Mars Shell Mark 2 2003 94 Y Shell designBalam GOM Pemex 2005 30

Clair BP Two stage 2005 100 Y Requires 80 kbwpd. T. Marsh note of 29/6 says best achievable through Minox is 35 kbwpd

Holstein BP Mark 3 2005 100 NP 18 (Brazil) Petrobras 2005 150Thunderhorse GOM BP Two stage 2005 200

Bonga Shell Mark 3 2005 400 N Minox in permanent bypass due to blower bearing problems. Relying on Oxy Scavenger injection.

Agbami (W. Africa) Chevron 2006 450 - Under installation 10/06Atlantis GOM BP Two stage 2006 75

Ursa (future) Shell Mark 2 2008 - Shell design with large vessels, internals and scrubbers (SRM: cannot inject de-foamer)



Gas Blower

DeOx Unit

Gas/Gas HEx hard scale deposit

Problems w/MarsBijupira-SalemaBonga

Electric Heater

! Salt deposits! Vessels full of foam! Catalyst fouling / short catalyst life! Compressor fouling / high maintenance

catalyst fouling



G/L Separation Design& differences system to system:

Almost all conventional HC G/L systems havescrubbers U/S of compressors, yet thissystem has:

No scrubbersLimited coalescing filtersNo membrane filters

MeOHGas CompressorHex / Heater

CatalystBed

1st StageSeparator

2nd StageSeparator

Typical Minox Unit:

Residence Time(sec)

WF1 19WF2 25WF3 30WF4 91

cross-sectional area: sq ft

Gas flux: cubic feet per minute

notevariation

droplet entrainment

carry-under

cfm/sq ft cm/hour/sq mWF1 21 382WF2 16 288WF3 14 257WF4 8 143Auger HP Vert Sep 6 110

Carry-Over & Carry-Under:



0.0

1.0

2.0

3.0

4.0

5.0

6.0

0.0 1.0 2.0 3.0 4.0 5.0foam height (inch)

foam

life

time

(min

utes

)

Foam Lifetime as a function of Foam Height

Lab Scale Study : > low gas rate > small bubble sizehigh lifetime at small height

Minox Separator Vessel SizingShould Account for Foam Height Vessel Design should include Foam Height:

GFOV HHHH ++=

rate(BPM)flowoilfoam/BPM)(ftratioOiltoFoamintrinsic

less)(dimensionFactorGeometryHeightFoamconstant

3

1

==

==

O

F

F

FEkk

spec) (Shellsection gas ofheight section foam ofheight

minute) 1 time(retentionsection oil ofheight

==

==

G

F

O

HHH

oFFF

VFF

FEkkVAVH

1

/==

20 secondswater retention

ID = 6 ft60 seconds

water retentionID = 10 ft

G = 3.5 ftO = 4.5 ftH = 8.0 ft

G = 3.5 ftMesh (2) = 2.5 ftF = 4.0 ftO = 4.5 ftH = 14.5 ft

FO = 65 BPM Scrubber

When upper layers burst, liquid drains into lower

layers making them stronger. Thus, a tall

foam is a strong foam.

Foam Volume (ft3): 54 54 54Surface Area (ft2): 36 18 9Foam Height (ft): 1.5 3 6Foam Lifetime (minutes): 0.5 3 17

Vessel Geometry Effect onFoam Height & Foam Lifetime

Foam bubbles burst across the top surface. Thus, higher surface

area increases burst rate.



Foam Height versus DeOx Vessel Inside Diameter:

02468

101214161820

8 9 10 11 12 13 14vessel ID (ft)

foam

hei

ght (

ft)

foaminess index: 0.1 0.15 0.2

Foam height as a function of vessel ID and foaminess index for the UPWF Minox separators:

Bonga Foaminess Index 0.134 cu ft / BPM Vessel ID 8.43 ft Liquid flux rate 1.9 BPM / sq ft Foam height 3.30 ft

Seawater / Nitrogen Foam Height Design Curves:

Calibration usingBonga Data:

UPWF design



Inst Air

To Injection Pumps

From Fine

Filters

Drain Drain

Minox System. Possible Upgrades shown in red

Atm. Vent

Check valve or SDV?

Atm. Vent

Outlet LCV here or at PCV3200 as

Mars?

Scrubber on catalyst inlet?

Scrubber oncompressor suction?

Nitrogen Backup MEOH

Injection

Backup Antifoam Injection

Replace LCV‘s for control /

isolation

Spre compressor?

Gas oxygen analyzer?

High Capacity O2 scav linked

to bypass

Gas oxygen analyzer?

FCV, FIC?



WaterfloodFeed Pumps

StrainersCartridge

Filters

0

1

2

3

4

5

6

7

8

9

DP

(PS

I)

0

2 0 0

4 0 0

6 0 0

8 0 0

1 0 0 0

1 2 0 0

1 4 0 0

1 6 0 0

(SC

FM)

Overlay of Air Makeup & Strainer BackwashWF2 Complex Oxygen Control Response

Air Makeup

0123456789

Delta

P (P

SI)

02004006008001000120014001600

SCFM

Separator Level control converted to direct control

Added a FIC / FCV upstream of the 1st stage separator

Changed the instrument gas pressure regulator to a FIC / FCV



Level / Flow Control for the DeOx / High Pressure Pump system

Seawater

OverboardDischarge

2nd Stage DeOxNitrogen

OverboardDischarge

LT

PT

! Operating experience: frequent trips on startup of HP pumps! PIT instead of a FIT –

sensitive dP / Q relation but too nonlinear

Booster PumpsLT

FQI

OverboardDischarge

OverboardDischarge

2nd Stage DeOx

Seawater

Nitrogen

WF1-problems WF2-successful! Operating experience: no trips on startup of pump systems! LIC / LCV tied to overflow / discharge line –

effective for rapid flow control / response ! Flow sensor tied to overflow / discharge line –

effective over broad range of startup & normal operating conditions



Third-Party Review:• sealing and salt deposition problems in the nitrogen blowers• inability of the system to respond automatically to flow or temperature changes• high degree of operator intervention required• lack of engineering and service capability within Minox Technology• In addition to the above, doubts remain about the capability of the separators to achieve adequate separation without making them substantially larger.

The Minox unit for Holstein as delivered from Kvaerner Process Systems required instrumentation upgrades and de-bottlenecking. These upgrades included: 1. oxygen gas phase analyzers installed on inlet and outlet of the deoxidizer, 2. temperature indicators installed in the same locations as the gas phase oxygen analyzers, 3. methanol flow measurement and control, 4. instrument air flow measurement and control, 5. instrument air coalescing filters, 6. replacement of a Big Joe regulator to a PCV on second stage separator, 7. single 16” static mixer on separator inlets versus two mixers (10” and 12”) in parallel for turn down, 8. changed 50 hp to 60 hp blower driver, 9. increase deoxidizer catalyst bed volume, 10. installed methanol atomizing quill, 11. automated Minox inlet and by pass valves, 12. installed methanol and Instrument air mixing orifice, 13. made logic changes from sea water level to flow control 14. Tie-in of all Minox system input / output into the platform Honeywell DCS.

Holstein Upgrades:



0

1000

2000

3000

4000

5000

0 50 100 150 200 250Water Rate (MBWPD)

Dai

ly C

ost (

$/da

y)

0

500,000

1,000,000

1,500,000

Ann

ual C

ost

Opex Cost Considerations:

Scavenger: ppm rate depends on water T and source depthHolstein: 50 ppm (-650 feet from NSL)Bonga: 55 ppm (warm water)Brazil: 45 ppm (warm water)Mars: 80 ppm

Minox:MeOHpolishing scavengerdefoamercatalyst replacement cost

100 ppm

Minox

50 ppm



Hypo / Oxygen Scavenger / Biocide Injection:

TypicalWell

CourseFilters

FineFilters

SeawaterLift

Pumps

PT

Hypo

Oxy scav is incompatible w/ hypo, which exposes D/S piping to biofilm.

Org biocide is incompatible w/ oxy scav which causes an oxygen excursion when batch biocide is performed.

Thus, oxy scav must be nearly fully reacted before batch biocide addition. Also, a flush biocide treatment can be performed during S/D.

Guidelines for Biomonitoring & Control should be followed.

There are other small but important design details that must be incorporated for long term integrity using chemical.

Global Category Management is working on this Guideline.

Biocide

Oxygen scavenger

Biocide



Other options:Stripping towerVacuum tower

Even with these, break dependence on production uptime for power, gas, etc need to switch to chemical to achieve waterflood uptime

However with chemical only systems, need to have high quality injection equipment plant uptime, sparing, automated flow control, alarm measurement, etc.,Need residence time, and tanks

Weight space cost comparisons logistics storage uptimevs Brazil & Bonga uptime 95% +

Guidelines for the Selection of a Waterflood Deoxygenation …petrowatertech.com/wp-content/uploads/2015/08/Deuel... · · 2015-08-24of a Waterflood Deoxygenation Strategy C. Deuel

Documents