The Oyster Bayou CO 2 Flood Case History. Alton Ahrens, Denbury Resources

Transcription

1 The Oyster Bayou CO 2 Flood Case History Alton Ahrens, Denbury Resources N Y S E : D N R w w w. d e n b u r y. c o m

2 Table of Contents o Highlights of the CO2 Flood o Pre-CO 2 History o o o Location and Structure Map of Oyster Bayou Reservoir Data and Pre-CO 2 Development Oyster Bayou Production History o CO 2 Development o Well Zone Completions o Water Injection Performance o Performance N Y S E : D N R 2 w w w. d e n b u r y. c o m

3 Highlights of the CO2 Flood N Y S E : D N R 3 w w w. d e n b u r y. c o m

4 Summary o Oyster Bayou CO 2 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 N Y S E : D N R 4 w w w. d e n b u r y. c o m

5 Pre-CO 2 History N Y S E : D N R 5 w w w. d e n b u r y. c o m

6 Location and Structure Map of Oyster Bayou CHAMBERS COUNTY 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 NYSE:DNR 6 w w6w. d e n b u r y. c o m

7 Reservoir Data and Pre-CO 2 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 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 / 39.7 Oil Recovered (Pre-CO 2 ), million STB 142 Oil Recovery Factor (Pre-CO 2 ), % 62.8 Discovered with gas cap N Y S E : D N R 7 w w w. d e n b u r y. c o m

8 Oyster Bayou Production History Water Injection Starts 1950 Water Injection Ends 1997 Gas Cap Blowdown 1995 CO2 Injection Starts 2010 Denbury Purchase 2007 N Y S E : D N R 8 w w w. d e n b u r y. c o m 8

9 CO 2 Development N Y S E : D N R 9 w w w. d e n b u r y. c o m

10 Before Facility was built o Removed old facilities o Grading in new location N Y S E : D N R 10 w w w. d e n b u r y. c o m

11 Facility o Gas Fired Compressors o Central gathering and processing o Central testing 1000 feet N Y S E : D N R 11 w w w. d e n b u r y. c o m

12 Pictures of the field N Y S E : D N R 12 w w w. d e n b u r y. c o m

13 1st Injection June of 2010 N Y S E : D N R 13 w w w. d e n b u r y. c o m

14 Pre-CO 2 Flood Predictions from Simulation How close were they?? o Strong Gravity Override of CO 2 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 CO 2 Utilization 12.4 MSCF/STB to 17.1 MSCF/STB o Gross CO 2 Utilization 55.1 MSCF/STB to 69.6 MSCF/STB N Y S E : D N R 14 w w w. d e n b u r y. c o m

15 CO 2 Development Details Wells Number Reservoir Operating Pressure 4,000 psi MMP 4,000 psi CO 2 Flood Type Miscible Producer wells 30 Injector wells 24 HP Compression, MMscf/d 259 LP Compression, MMscf/d 16 Current CO 2 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 Development Area OOIP A1 / A2, MMBO / 25.5 Cum Gross Tertiary Prod A1 / A2, MMBO 8.9 / 3.1 Cum Tertiary Recovery Factor A1 / A2, % 5.5 / 12.1 N Y S E : D N R 15 w w w. d e n b u r y. c o m

16 Cum CO 2 Oil to Date from A1 and A2 Wells N Y S E : D N R 16 w w w. d e n b u r y. c o m

17 Well Zone Completions N Y S E : D N R 17 w w w. d e n b u r y. c o m

18 A1 contribution from each zone (total of 4 identified here) Peach 1 (Upper A1) Green 2 Blue 3 Purple 4 (Lower A1) N Y S E : D N R 18 w w w. d e n b u r y. c o m

19 A1 Net and Gross Utilization to date N Y S E : D N R 19 w w w. d e n b u r y. c o m

20 Mid Development Change Isolated A2 Injection and Production MONTHLY NET UTILIZATION (MCF/BO) Isolated A2 perforations in 6 injection wells Jan-13 Apr-13 Jul-13 Oct-13 Jan-14 Apr Historically, injection logs indicate <15% total injection to A2. Example is typical of other injectors. A2 was subsequently isolated in this well N Y S E : D N R 20 w w w. d e n b u r y. c o m 20

21 Current Development Dedicated A1 & A2 Floods 8,000 7,000 OYSTER BAYOU AVERAGE BOPD BY ZONE A1 A2 START OF DEDICATED A2 FLOOD 6,000 5,000 4,000 3,000 2,000 1, /10 12/10 06/11 12/11 06/12 12/12 06/13 12/13 06/14 12/14 06/ OYSTER BAYOU AVERAGE MMCF INJ BY ZONE A1 A2 ISOLATE A2 PERFS IN SEVERAL INJECTORS /10 12/10 06/11 12/11 06/12 12/12 06/13 12/13 06/14 12/14 06/15 N Y S E : D N R 21 w w w. d e n b u r y. c o m 21

22 A2 Development Area A2 contributions by zone Blue Upper A2 Light Blue Lower A2 N Y S E : D N R 22 w w w. d e n b u r y. c o m

23 A2 Net and Gross Utilization to date N Y S E : D N R 23 w w w. d e n b u r y. c o m

24 Water Injection Performance Or why we are recovering more than expected with CO 2 N Y S E : D N R 24 w w w. d e n b u r y. c o m

25 Water Injectivity problems in A1 and A2 sand 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. N Y S E : D N R 25 w w w. d e n b u r y. c o m

26 Performance N Y S E : D N R 26 w w w. d e n b u r y. c o m

27 Re-pressurization history N Y S E : D N R 27 w w w. d e n b u r y. c o m

28 Processing Rate N Y S E : D N R 28 w w w. d e n b u r y. c o m

29 A1 GOR vs Oil Cumulative and Dimensionless Recovery Curve PDP assuming no further work Reservoir OOIP Cum to date As of 9/2018 Recovery Factor As of 9/2018 A1 162,497 MBO 8,909 MBO 5.5% N Y S E : D N R 29 w w w. d e n b u r y. c o m

30 A2 GOR vs Oil Cumulative and Dimensionless Recovery Curve PDP assuming no further work Reservoir OOIP Cum to date As of 9/2018 Recovery Factor As of 9/2018 A2 25,536 MBO 3,099 MBO 12.1% N Y S E : D N R 30 w w w. d e n b u r y. c o m

31 OOIP & Recovery Factor Table Reservoir OOIP Cum to date As of 9/2018 Recovery Factor As 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 work Many improvements can be made in the future with conformance work N Y S E : D N R 31 w w w. d e n b u r y. c o m