The Oyster Bayou CO2 Flood Case History · Oil Recovered (Pre-CO 2), million STB 142 Oil Recovery...
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www.denbury.com NYSE:DNR The Oyster Bayou CO 2 Flood Case History Alton Ahrens, Denbury Resources
Transcript of The Oyster Bayou CO2 Flood Case History · Oil Recovered (Pre-CO 2), million STB 142 Oil Recovery...
w w w . d e n b u r y . c o mN Y S E : D N R
The Oyster Bayou CO2Flood Case History
Alton Ahrens, Denbury Resources
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o Highlights of the CO2 Flood
o Pre-CO2 Historyo Location and Structure Map of Oyster Bayou
o Reservoir Data and Pre-CO2 Development
o Oyster Bayou Production History
o CO2 Development
o Well Zone Completions
o Water Injection Performance
o Performance
Table of Contents
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Highlights of the CO2 Flood
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o Oyster Bayou CO2 flood has been very successful
o Weak aquifer allowed a quick fill-up
o High remaining oil saturation due to the lack of a strong water drive and poor waterflood of the A2
o Early breakthrough was not an issue (good conformance)
o Gas fired compression successfully implemented
o Small facility footprint
Summary
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Pre-CO2 History
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CHAMBERSCOUNTY
Location and Structure Map of Oyster Bayou
• Field discovered April 21, 1941• Located 50 miles E of Houston• Frio Sand; Faulted Anticline Structure• Gas Cap Expansion reservoir with small aquifer and
peripheral water injection• 2300 acres developed with 52 oil wells drilled on 40
acre spacing
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Reservoir Data and Pre-CO2 Development
Producing Formation Names A1 / A2 (Frio)
Datum Depth / GOC / WOC, ft ss 8240 / 8180 / 8391
Temperature, °F 190
Initial Pressure and Saturation Pressure, psig 3800
API Gravity 39.5
Gas Gravity 0.63
Water Salinity, ppm 60,000
Formation Volume Factor, rb/STB 1.354
Average Porosity A1 / A2, % 28.5 / 27.8
Average Perm A1 / A2, md 2000 / 275
Average Swi A1 / A2, % 16 / 31.1
Net Thickness, ft 115.6 / 39.7
Oil Recovered (Pre-CO2), million STB 142
Oil Recovery Factor (Pre-CO2), % 62.8
Discovered with gas cap
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Oyster Bayou Production History
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Water Injection Starts 1950
Water Injection Ends 1997
Gas Cap Blowdown 1995
CO2 Injection Starts 2010
Denbury Purchase 2007
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CO2 Development
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o Removed old facilities
o Grading in new location
Before Facility was built
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o Gas Fired Compressors
o Central gathering and processing
o Central testing
Facility
1000 feet
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Pictures of the field
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1st Injection June of 2010
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o Strong Gravity Override of CO2 at all Stages
o Full Zone Well Completions Best
o A2 Sand Response/Contribution Insignificant
o A1 Oil Recovery – 9.7% to 12.0% of OOIP
o Net CO2 Utilization – 12.4 MSCF/STB to 17.1 MSCF/STB
o Gross CO2 Utilization – 55.1 MSCF/STB to 69.6 MSCF/STB
Pre-CO2 Flood Predictions from SimulationHow close were they??
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CO2 Development Details
Wells Number
Reservoir Operating Pressure 4,000 psi
MMP 4,000 psi
CO2 Flood Type Miscible
Producer wells 30
Injector wells 24
HP Compression, MMscf/d 259
LP Compression, MMscf/d 16
Development Area OOIP A1 / A2, MMBO 162.5 / 25.5
Cum Gross Tertiary Prod A1 / A2, MMBO 8.9 / 3.1
Cum Tertiary Recovery Factor A1 / A2, % 5.5 / 12.1
Current CO2 Development:• A1 and A2 being flooded separately• A1 patterns on 160 acre 9-spots• A2 patterns on 80 acre 5-spots• Oil production ~5,700 bbl/day
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Cum CO2 Oil to Date from A1 and A2 Wells
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Well Zone Completions
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A1 contribution from each zone (total of 4 identified here)
Peach 1 (Upper A1)Green 2Blue 3Purple 4 (Lower A1)
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A1 Net and Gross Utilization to date
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MONTHLY NET UTILIZATION (MCF/BO)
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Mid Development Change Isolated A2 Injection and Production
Historically, injection logs indicate <15% total injection to A2. Example is
typical of other injectors. A2 was subsequently isolated in this well
0
25
50
75
100
125
150
10
20
30
40
50
60
70
Jan-13 Apr-13 Jul-13 Oct-13 Jan-14 Apr-14
Isolated A2 perforations in 6 injection wells
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Current Development –Dedicated A1 & A2 Floods
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
06/10 12/10 06/11 12/11 06/12 12/12 06/13 12/13 06/14 12/14 06/15
OYSTER BAYOU AVERAGE BOPD BY ZONE
A1 A2
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
06/10 12/10 06/11 12/11 06/12 12/12 06/13 12/13 06/14 12/14 06/15
OYSTER BAYOU AVERAGE MMCF INJ BY ZONE
A1 A2
START OF DEDICATED A2 FLOOD
ISOLATE A2 PERFS IN SEVERAL INJECTORS
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A2 Development Area
A2 contributions by zoneBlue Upper A2Light Blue Lower A2
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A2 Net and Gross Utilization to date
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Water Injection PerformanceOr why we are recovering more than expected with CO2
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o Reservoir damage due to previous water flooding
o The dominant clay type is Smectite (swelling) followed by mix. Smectite/Illite.
o The majority of the examined thin sections show damaged textures.
o A2 has more swelling clay and feldspars percentage compared to A1.
Water Injectivity problems in A1 and A2 sand
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Performance
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Re-pressurization history
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Processing Rate
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A1 GOR vs Oil Cumulative and Dimensionless Recovery Curve
Reservoir OOIP Cum to dateAs of 9/2018
Recovery FactorAs of 9/2018
A1 162,497 MBO 8,909 MBO 5.5%
PDP assuming no further work
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A2 GOR vs Oil Cumulative and Dimensionless Recovery Curve
Reservoir OOIP Cum to dateAs of 9/2018
Recovery FactorAs of 9/2018
A2 25,536 MBO 3,099 MBO 12.1%
PDP assuming no further work
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OOIP & Recovery Factor Table
Reservoir OOIP Cum to dateAs of 9/2018
Recovery FactorAs of 9/2018
A1 162,497 MBO 8,909 MBO 5.5%
A2 25,536 MBO 3,099 MBO 12.1%
Total 188,033 MBO 12,008 MBO Avg. RF 6.4%
PDP assuming no further workMany improvements can be made in the future with conformance work
