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Home My WebLink About2001 Tarn Oil PoolPHI PHILLIPS Alaska, Inc. A Subsidiary of PHILLIPS PETROLEUM COMPANY P.O. BOX 100360 ANCHORAGE, ALASKA 99510-0360 March 28, 2002 Ms. Camille Oechsli Taylor, Commissioner Alaska Oil and Gas Conservation Commission 333 West 7th Ave. Suite #100 Anchorage, Alaska 99501-3539 John L. Hand Supervisor Greater Kuparuk Area Reservoir Planning ATO 1228 Phone 265-6036 Fax: 265-6133 Re: 2001 Tarn Oil Pool Annual Reservoir Surveillance Report Dear Ms. Oechsli Taylor: In compliance with Rule 11, Conservation Order No. 430, Phillips Alaska, operator of the Kuparuk River Field, is hereby submitting the annual report on the Tarn Oil Pool. This report documents the required information pertinent to the field development and enhanced recovery operations from January through December 2001. The following is an outline of the information provided: a. A summary of the enhanced recovery project (Attachment 1). b. Voidage balance, by month, for produced and injected fluids (Attachment 2, Attachment 3). c. Analysis of reservoir pressure surveys taken in 2001 (Attachment 4). d. Results of production surveys, and any special surveys, taken on the Tarn Oil Pool in 2001 (Attachment 5). e. Results of well allocation and test evaluation for Rule 7, and any other special monitoring (Attachment 6). f. Development Plan and Operation Review (Attachment 7). If you have any questions concerning this data, please contact Bob Christensen at (907) 659-7535 or Jason Putnam at (907) 265-6970. Sincerely, 9n L. Hand GKA Reservoir Planning Supervisor nEcEV.ED MAR 2 8 2002 oN A bcc: Central Files John Braden John Hand Dan Kruse Jason Putnam Bob Christensen Michael Balog & Grant Doman Mark Stevenson ATO — 320 ATO — 1276 ATO — 1228 ATO — 1220 ATO — 1206 NSK — 69 NSK — 69 ATO — 1232 Attachment 1 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Summary of the Enhanced Recovery Project Background In 1998 AAI received approvals for formation of the Tarn Oil Pool in the Kuparuk River Unit, an Area Injection Order for Tarn, expansion of the Kuparuk River Unit and formation of the Tarn Participating Area. The Tarn Pool Rules and Area Injection Order were approved on July 21 st and July 20t"' respectively. The Unit Expansion and Participating area were approved effective July 1, 1998. Construction of the Tarn road, pads, powerlines and pipelines took place in the 1998/1999 winter construction season. Tarn development drilling commenced in April of 1998. Tarn production began on July 8, 1998. Injection of miscible injectant (MI) began in November 1998. By year-end 2001, forty-one Tarn development wells had been drilled. Progress of FOR Project New development activity in 2001 consisted of drilling four additional development wells, bringing the total number of Tarn wells to forty-one. The permanent 12" water injection line was completed and brought on-line in July 2001. This has allowed Tarn to switch from strictly an MI flood to an MWAG recovery process which will increase ultimate recovery from the Tarn reservoir. Water injection capacity has been good and injectivity has remained strong after 8 months of continuous water injection with no signs of formation damage. Tarn is operating at injection pressures above parting pressure which enables water injection to match offtake. Reservoir Management Summary In 2001, Tarn produced 8.05 MMSTB oil, 0.22 MMBW water and 15,540 MMSCF gas. The injection totals for 2001 were 15,040 MMSCF of MI and 11.45 MMBW water. The cumulative yearend I/W ratio for DS 2N is estimated at 0.92, while the estimated cumulative I/W for DS 2L is 1.13. The monthly average I/W ratios for DS 2N and 2L in December 2001 were 1.13 and 1.50 respectively. Because the cumulative I/W is less than 1.0 in the 2N area, some pressure depletion has occurred and a reservoir management strategy was initiated in October 2000 in an effort to increase reservoir pressure in the 2N area. Re - pressurization has been accomplished through a strategic combination of increased injection and reduced withdrawals in order to maintain I/W ratios greater than 1.0. In order to increase injection several new wells were drilled during 2001 along with two producer -to -injector conversions completed in early 2002. The reservoir responded well during 2001 to the re -pressurization strategy, with sharp decreases in the formation gas -oil ratio and strong increases in oil production rate across DS-2N. Once a cumulative I/W of 1.0 is reached in the 2N area, plans are to maintain reservoir pressure by balancing monthly injection and production rates. Attachment 2 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Produced Fluid Volumes OIL GAS WATER CUM OIL CUM GAS CUM WATER MO YR STB MSCF BBL STB MSCF BBL 1 2001 577297 1341390 1583 22422406 36993316 1084755 2 2001 508756 1242769 2572 22931162 38236085 1087327 3 2001 662677 1565493 1905 23593839 39801578 1089232 4 2001 657935 1366653 1326 24251774 41168231 1090558 5 2001 648931 1398487 937 24900705 42566718 1091495 6 2001 619686 1369152 654 25520391 43935870 1092149 7 2001 627361 1399360 10477 26147752 45335230 1102626 8 2001 723034 1499019 40087 26870786 46834249 1142713 9 2001 639985 1155007 39852 27510771 47989256 1182565 10 2001 660500 1034482 31093 28171271 49023738 1213658 11 2001 794120 958930 35387 28965391 49982668 1249045 12 2001 932150 1207578 54764 29897541 51190246 1303809 2001 TOTAL 8052432 15538320 220637 Last years cum 21845109 35651926 1083172 Attachment 3 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Injected Fluid Volumes WATER GAS NGLS CUM WATER CUM GAS CUM NGLS MO YR STB MSCF MSCF STB MSCF MSCF 1 2001 0 0 2095659 3143386 0 36344082 2 2001 0 0 2196489 3143386 0 38540571 3 2001 53 0 2605062 3143439 0 41145633 4 2001 0 0 2569653 3143439 0 43715286 5 2001 0 0 2467274 3143439 0 46182560 6 2001 0 0 2040249 3143439 0 48222809 7 2001 1457358 0 251653 4600797 0 48474462 8 2001 2386413 0 0 6987210 0 48474462 9 2001 2208442 0 0 9195652 0 48474462 10 2001 1728771 0 38478 10924423 0 48512940 11 2001 1865411 0 269225 12789834 0 48782165 12 2001 1805148 0 505437 14594982 0 49287602 2001 TOTAL 11451596 0 15039179 Last years cum 3143386 0 34248423 Attachment 4 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Reservoir Pressure Surveys Tarn reservoir pressure is referenced to a depth of 5200' ss. Production commenced at 2N pad in July of 1998. Initial reservoir pressure measurements ranged from 2300-2350 psi. Production commenced at 2L pad in December of 1998. Consistent with 2N pad, the range on initial reservoir pressure measurements was 2330-2385 psi. Rule 8 Format Follows for 1st 2nd3rd, and 4t" Quarters Attachment 5 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Production Logs and Special Surveys Injection surveys were conducted at drill site 2N to evaluate vertical conformance while injecting miscible gas and water. Results from the surveys were referenced to the latest stratigraphic framework of the Bermuda pay interval to allocate injection to distinct turbidite sequences. The interpreted reservoir architecture is summarized below: Lavender Sequence (crevasse splay - limited potential) Upper Blue Sequence (present only in the south) Blue Sequence (present only in the south) Red Sequence (present only in the north) Green Sequence (present only in the north) Rose Sequence (present over most of the field) Dark Blue Sequence (present only in the south). WELL SVY DATE FLUID RATE Iniection Splits MMCFPD/BWPD UPPER BLUE BLUE RED GREENJ ROSE DARK BLUE 2N-307 4/28/2001 MI 9.5 0.58 0.42 0.00 2N-307 11 /9/2001 W 1 10020 0.43 0.44 0.13 2N-321A 5/14/2001 MI 7.3 0.51 0.40 0.09 2N-321A 5/14/2001 MI 1 14 0.45 0.45 0.10 2N-321 A 10/26/2001 W I 1 10092 0.42 0.40 0.18 2N-325 4/29/2001 MI 14.2 0.05 0.95 2N-325 11 /11 /2001 W 1 8500 0.00 1.00 2N-331 4/26/2001 MI 15.0 0.04 0.21 0.75 2N-331 4/26/2001 MI 5.0 0.12 0.15 0.73 2N-331 4/27/2001 MI 5.0 0.16 0.15 0.69 2N-331 11 /11 /2001 W 1 10500 0.00 0.00 1.00 2N-343 5/13/2001 MI 10.2 0.02 0.98 0.00 2N-343 11/13/2001 WI 1 14500 0.00 0.89 0.11 2N-349A 1/2/2001 MI 9.8 0.00 1.00 2N-349A 4/30/20, 1 MI 3.0 0.00 1.00 2N-349A 11/13/2001 WI 2400 0.00 1.00 Attachment 6 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Well Allocation and Test Evaluation Summary Produced fluid volumes were tracked through the Setcim production monitoring system and producing wells were tested a minimum of two times per month. During the first nine months of 2001 the 2L and 2N Accuflow test separator continued to undergo weekly hot diesel flushes to minimize paraffin deposition problems and maintain the accuracy of the test data. Once the jet pumped wells came on-line in October, hot diesel flushes were cut back to one every 6 to 8 weeks due to the decrease in paraffin deposition with the hot power fluid in the produced fluids. Production allocation to Tarn continued to be based upon an allocation factor of 1.0 in 2001. Attachment 7 Kuparuk River Unit Tarn Oil Pool 2001 Annual Reservoir Surveillance Report Tarn Development Plan and Operational Review Development Drilling — Four wells were drilled successfully at DS-2N during the fourth phase of development drilling at the Tarn reservoir. At this time there are no specific plans to drill additional wells in the near future at DS-2L or 2N; however, infill wells and/or additional development wells may be identified as the Tarn field matures and additional data is gathered. MI/Water Injection — Construction of a 12" water injection line out to the Tarn drill sites was completed in 2001 and was brought on-line in July 2001. Surface facilities associated with the water line were also completed at that time, allowing individual injectors the capability to inject either MI or water. Artificial Lift — The majority of gas lifted wells were converted to hydraulic jet pump artificial lift during the summer of 2001 after the completion of the 12" water injection line. Once water breakthrough occurs, the jet pumps will become more inefficient and those wells will begin to be switched back to a gas lift mechanism. It is projected that once MI has been fully utilized at both Tarn and Meltwater for EOR, the 8" gas injection line will be converted from MI to lean gas. This lean gas will then be used to lift the wells. Producer to Injector Conversions — Two wells, 2N-326 and 2N-335, were converted to injection service during early 2002. Future conversions are being evaluated in order to continue to reduce the producer/injector ratio and move Tarn towards a 5-spot injection pattern. In the short-term, increasing the number of injectors will allow Tarn to accelerate its move to a cumulative I/W of 1.0 at Drillsite 2N (southern lobe). In the long-term, the conversions will improve sweep efficiency and help to maximize recovery from the Tarn field. Freeze Protection/Subsidence - Plans to change Tarn from a continuous MI flood to a MWAG recovery process requires modifications to the existing surface facilities. Introduction of water to the system results in the need for freeze protection of the surface piping and well heads. Installation of well houses and associated equipment began in 2001 at Drill Sites 2L and 2N to provide this protection. In addition, subsidence mitigation began to be addressed during 2001 with well shelter floors and thermo-siphons.