SPE 101681

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SPE 101681

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From Concept to Pilot to Full-Field
Implementation A New EOR Process for the Prudhoe
Bay Field
SPE 101681

• P. L. McGuire, F. H. Carini, J. G. Ambrose,
• A. N. Yancey, M. N. Panda, BP Alaska

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Outline

• Background of Updip Zone 4
• Process Comparison Cores
• History Match of Production Core Data
• Process Comparison Study
• Field Tests
• Staged Development
• Overall Conclusions

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Prudhoe Bay Type Log
50 meters
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Prudhoe Bay Zone 4 Process Cores
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D-06A Gravity Drainage Process Core

• Cored in July 1997
• Core taken 600 ft from old D-06 producer
• Placed on production in 1977
• Cumulative production of 23 MMSTB
• Top 40 ft in original gas cap
• Mature Gravity Drainage pattern

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13-06A Waterflood/EOR Process Core

• Cored in January 1998
• Core taken 300 ft from old 13-05 producer
• Core taken 1500 ft from old 13-06 injector
• Placed on MI injection in 1984
• Cumulative injection of 17 TPV MI
• Mature WAG pattern

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D-06A vs 13-06A Logs
Waterflood/EOR
Gravity Drainage
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D-06A and 13-06A So vs. Depth
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D-06A and 13-06A So vs. Permeability
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Updip Zone 4 Cores
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Updip Zone 4 Core Permeability
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Updip Zone 4 Oil Target

• D-06A data shows high updip Zone 4 Sor
• UZ4 perms average much lower than D-06A
• Gravity drainage will leave high Sor in Zone 4
• 13-06A data shows Zone 4 WAG works well

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Updip Zone 4 Potential Flood Targetbetween
existing waterflood and original gas cap
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D-06A Simulation Analysis

• History match core oil saturations
• Identify mechanisms causing high Sor

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Oil saturation match of D-06A core
Heterogeneity Dominated
Capillary Pressure Dominated
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D-06A Conclusions

• High perm rock (gt800 mD) is draining well
• Modest perm rock (lt600 mD) is leaving a
  significant mobile oil target behind
• Shales are impeding the GD process
• History match simulation closely reproduced the
  oil saturations measured in the core

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13-06 Pattern Analysis

• History Match Production from Well 13-05
• History Match 13-06A Core
• Saturations
• Compositions

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Well 13-05 History Match Two Triangular Models,
40190 Cells
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Well 13-05 Oil Production History Match
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13-06 Pattern SimulationOil Saturation Map
13-06A
13-05
13-06
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13-06 Pattern SimulationPropane Mole Fraction Map
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Oil saturation match of 13-06A core
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Oil Composition Match of 13-06A Core
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13-06A Conclusions

• Good quantitative oil production history match
• Simulator reproduced the measured oil saturations
• Simulator reproduced the measured oil
  compositions
• Shale description in model is reasonable
• Simulator is capturing proper mechanisms

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Updip Zone 4 Strip Model

• Investigate Updip Zone 4 oil target
• Evaluate updip water and MI injection strategies
• Evaluate MI efficiency
• Evaluate sensitivity to reservoir description

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Updip Zone 4 Strip Model Schematic
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Updip Zone 4 Porosity and Permeability
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UZ4 Initial Saturations
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Oil Saturation after 12 months MI
SWIPE MI Oil Saturations
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Gas Saturation after 12 months MI
SWIPE MI Gas Saturations
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Oil Saturation after 10 years WF vs GD
So Waterflood vs Continued GD
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Updip Zone 4 Strip Model Oil Rates
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Updip Zone 4 Cum Incremental Oil
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Updip Zone 4 EOR Mechanisms

• Secondary MI, not Tertiary
• Extremely Rich EOR Target
• 50 So vs. 25 So
• Dominated by Oil Swelling, not So Reduction
• Major injectivity increase of MI vs. Water
• Major rate acceleration
• Barrel-in / Barrel-out just like Waterflood
• No need to propagate EOR across reservoir

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UZ4 EOR Analysis

• Better performance than existing Prudhoe Bay EOR
• Very good gross and net MI efficiency
• Works with or without chase waterflood

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Updip Zone 4 Field Tests

• One Waterflood Pilot and One MI Pilot
• Proof-of-concept of high oil saturation target
• Proof-of-concept of excellent UZ4 EOR
• Determine safe water injection rates
• Establish water containment in Zone 4
• Validate Model

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Updip Zone 4 Pilot Injectors
MI
Waterflood
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DS 14-01A Updip Zone 4 MI Pilot

• Long-term shut-in for high GOR
• March 2000 injection startup
• Rich Gas injection terminated November 2001
• 23 Bscf cum MI
• Aaverage rate of 40 MMSCFD

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DS 14-01A Cross Section
Lower Zone 4 Production
Middle Zone 2
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DS 14-01A MI Injection Rates
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14-01A Pilot EOR Response
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14-01A Oil Rate vs. Model Predictions
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14-01A Cum Oil vs. Model Predictions
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14-01A Field vs Model EOR

• Model scaled to pattern PV
• Good prediction on MI injection rates
• Major response in less than 1 year
• Field response consistent with Model
• Timing far faster than traditional EOR
• Good quantitative match of oil production

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Updip Zone 4 EOR Mechanisms

• Secondary MI, not Tertiary
• Extremely rich EOR target
• 50 So vs. 25 So
• Dominated by Oil Swelling, not So reduction
• Major injectivity increase of MI vs. water
• Rate acceleration
• Barrel-in / Barrel-out just like Waterflood
• No need to propagate EOR across reservoir

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DS 1-11 Updip Zone 4 Waterflood Pilot

• High GOR producer (20-30 Mscf/Stb)
• Proof-of-concept for Updip Zone 4 Waterflood
• Utilize conservative injection rates
• 5,000 to 10,000 BWPD likely
• Must not compromise GD recovery in Zone 2
• Injection startup September 4, 2001
• Objective was to Contain Water in Zone 4
• Tritiated Water Tracer Injected September 28,
  2001
• Test 9 Offset Wells

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DS 1-11 Updip Zone 4 WF Pilot Map
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DS 1-11 Water Injection Rates
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DS 1-11 Oil Tracer Production Rates
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DS 1-11 Incremental Oil Production Rates
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DS 1-11 Updip Zone 4 Waterflood Pilot

• Injectivity consistent with expectations
• Good injection rates
• Good injection profiles
• Good injection response seen in 5 wells
• Oil rate increase
• Gas rate decrease
• No tracer seen in updip Zone 2 wells
• Injection contained within Zone 4

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Updip Zone 4 New Mainfield Patterns
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Eileen West End Updip Zone 4 target
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Eileen West End UZ4 Pattern Map
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Eileen West End UZ4 MI Rates
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Eileen West End UZ4 EOR Rates
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Updip Zone 4 Injection ProjectCurrent Status
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Updip Zone 4 Injection Project Summary

• Process Comparison Cores yielded valuable
  insights
• Gravity drainage efficiency is poor in Zone 4
• Large remaining oil target for injection project
• Process Comparison Study
• Large single MI slug
• Secondary oil-swelling process
• Chase waterflood
• Mechanisms and Model Results validated by Field
  Tests
• Rapid EOR response
• Excellent MI efficiency
• Staged Development over last few years
• Encouraging results
• Remaining Patterns likely developed in next few
  years
• MI, water availability
• Facilities constraints

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From Concept to Pilot to Full-Field
Implementation A New EOR Process for the
Prudhoe Bay Field