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Home My WebLink About2024 Northstar Oil Pool Hilcorp Alaska, LLC Post Office Box 244027 Anchorage, AK 99524-4027 3800 Centerpoint Drive Suite 1400 Anchorage, AK 99503 Phone: 907/564-5246 Gavin.Dittman@hilcorp.com April 1st, 2025 Brett Huber Sr, Chair Alaska Oil & Gas Conservation Commission 333 W. 7th Avenue, Suite 100 Anchorage, Alaska 99501-3539 RE: NORTHSTAR UNIT, NORTHSTAR FIELD, NORTHSTAR OIL POOL, STATE OF ALASKA, 2024 ANNUAL RESERVOIR REVIEW Dear Commissioner Huber: In accordance with Conservation Order No. 458A, Hilcorp Alaska, LLC (“Hilcorp”), as Operator, hereby submits for your review the following Annual Reservoir Review for the Northstar Field. This is the Annual Reservoir Review and corresponds to events during the 2024 calendar year. Note that the Northstar Field has been on production since November 2001. A. Progress of Enhanced Recovery Project and Reservoir Management Summary During 2024, no new wells were drilled or sidetracked in the Northstar Unit. Therefore, the locations of all the wells in the Northstar Unit have remained unchanged. Production and injection statistics are summarized in Table 1. Average daily oil production from the Northstar Oil Pool was 3629 bopd and average daily gas injection was 431 mmscfpd. The reservoir voidage balance values reported do not include oil production or gas injection from outside the Northstar Oil Pool. The outside pool production includes satellite well NS-34A and Kuparuk zone production. Kuparuk gas injection is also excluded. During 2023, gas injection was calculated to be 3840 thousand-reservoir barrels (MRB) more than reservoir voidage. At year end, the reservoir overall cumulative voidage replacement ratio was 1.0. The average reservoir pressure from surveys obtained in 2024 was 5109 psia. Hilcorp became the official Operator of the Northstar Field effective November 18, 2014. Page 2 As of 12/31/2024 Full year (1) As of Dec-23 (2) Producers 12 11 Injectors 4 4 2024 Cumulative Start- Up through 12/31/24 1,328,210 183,141,584 148,691,404 3,349,457,114 3,430,937 96,077,914 5,449,787 110,491,823 157,653,549 3,707,271,432 103,364 2,517,879 107,204 2,520,056 3,840 2,177 3,629 406,261 9,374 14,890 430,747 5,109 psiaAverage of surveys obtained in 2024 Water, BWPD Injection Water, BWPD Gas, MCFPD AVERAGE RESERVOIR PRESSURE DAILY AVERAGE RATE DATA 2024 Production Oil, BOPD Gas, MCF/D Gas (MCF) Balance (excludes satellite well NS-34A and Kup Production/Injection ) Cum Production (MRB) Cum Injection (MRB) Over/Under (MRB) Oil (BBL) Gas (MCF) Water (BBL) Injection Water (BBL) into NS10 & NS32 Disposal Well (1) Well count data reflects ONLY those wells which contributed to production/injection during the respective year (2) Active wells as of December 2024 PRODUCTION/INJECTION STATISTICS Production Table 1: NORTHSTAR FIELD 2024 OVERVIEW STATISTICAL SUMMARY WELL STATISTICS NOTES: Page 3 B. Voidage Balance by Month of Produced Fluid and Injected Fluids – 2023 C. Summary and Analysis of reservoir pressure surveys within the pool Static bottom hole pressures collected in 2024 are summarized below. D. Results and Analysis of Production and Injection log surveys, tracer surveys, observation well surveys and any other special monitoring No new Ivishak production profiles were obtained in 2024. E. Review of pool production allocation factors and issues over the prior year Theoretical production is calculated for each Northstar producing well on a daily basis. Month Oil, MRB Free Gas, MRB Water, MRB Total Voidage, MRB Year Cum, MRB Cum since start-up, MRB Total Injection, MRB Year Cum, MRB Cum since start-up, MRB Net Injection, MRB Year Cum, MRB Cum since start-up, MRB Jan-2024 274 9,137 153 9,564 9,564 2,424,079 9,505 9,505 2,422,356 -60 -60 -1,723 Feb-2024 255 8,684 152 9,092 18,656 2,433,171 8,652 18,156 2,431,008 -440 -500 -2,164 Mar-2024 258 9,232 175 9,665 28,321 2,442,836 9,149 27,305 2,440,157 -516 -1,016 -2,679 Apr-2024 237 8,595 172 9,003 37,324 2,451,839 8,958 36,264 2,449,115 -45 -1,061 -2,724 May-2024 204 8,239 154 8,597 45,922 2,460,437 8,555 44,819 2,457,671 -42 -1,103 -2,766 Jun-2024 227 7,579 135 7,941 53,863 2,468,378 7,895 52,714 2,465,566 -46 -1,149 -2,812 Jul-2024 229 7,991 151 8,371 62,234 2,476,749 8,363 61,077 2,473,929 -8 -1,157 -2,821 Aug-2024 209 6,059 82 6,350 68,584 2,483,100 7,389 68,466 2,481,317 1,038 -119 -1,782 Sep-2024 225 7,078 130 7,432 76,017 2,490,532 8,825 77,291 2,490,142 1,393 1,274 -389 Oct-2024 235 7,922 153 8,310 84,327 2,498,842 9,880 87,171 2,500,022 1,570 2,844 1,181 Nov-2024 234 8,617 170 9,021 93,348 2,507,863 9,927 97,098 2,509,950 906 3,750 2,087 Dec-2024 249 9,609 159 10,016 103,364 2,517,879 10,106 107,204 2,520,056 90 3,840 2,177 2024 Totals 2,836 98,741 1,787 103,364 107,204 3,840 Produced Fluids Injected Fluids Net Injection (Injection - Production) 6. Oil Gravity: 44 API/47 API 8. Well Name and Number: 9. API Number 50XXXXXXXXXXXX NO DASHES 10. Type See Instructions 11. AOGCC Pool Code 12. Zone 13. Perforated Intervals Top - Bottom TVDSS 14. Final Test Date 15. Shut-In Time, Hours 16. Press. Surv. Type (see instructions for codes) 17. B.H. Temp. 18. Depth Tool TVDSS 19. Final Observed Pressure at Tool Depth 20. Datum TVDSS (input) 21. Pressure Gradient, psi/ft. 22. Pressure at Datum (cal) NS-06 50029230880000 O 590100 Ivishak 10901-11099 8/10/2024 288 SBHP 253 11099 5108 11100 0.16 5108 NS-19 50029231220000 O 590100 Ivishak 10954-11069 8/11/2024 8064 SBHP 253 11000 5088 11100 0.09 5097 NS-09 50029230520000 O 590100 Ivishak 10932-11030 7/18/2024 312 SBHP 236 10399 5033 11100 0.10 5100 NS-15 50029230730000 O 590150 Kuparuk 8940-8994 8/16/2024 11232 SBHP 193 9000 2974 9000 0.42 2974 NS-23 50029231460000 O 590150 Kuparuk 8953 - 9009 8/15/2024 5760 SBHP 195 9100 3028 9000 0.42 2986 NS-11 50029233030000 O 590100 Ivishak 10988 - 11058 2/4/2024 984 SBHP 252 11000 5097 11100 0.09 5106 NS-12 50029230910000 O 590100 Ivishak 10996 - 11057 8/12/2024 96 SBHP 251 11000 5084 11100 0.09 5093 NS-24 50029231110000 O 590100 Ivishak 10826 - 11047 8/14/2024 17664 SBHP 248 10999 5056 11100 0.44 5100 NS-20 50029231180000 O 590150 Kuparuk 9012 - 9059 1/19/2024 24 SBHP 196 9000 2735 9000 0.44 2735 STATE OF ALASKA ALASKA OIL AND GAS CONSERVATION COMMISSION RESERVOIR PRESSURE REPORT 1. Operator: 2. Address: Printed Name Title Date Reservoir Engineer March 7, 2025Gavin Dittman Certified Digital Signature 23. All tests reported herein were made in accordance w ith the applicable rules, regulations, and instructions of the Alaska Oil and Gas Conservation Commission. I hereby certify that the foregoing is true and correct to the best of my knowledge. 7. Gas Gravity: Northstar Unit Hilcorp Alaska, LLC 3800 Centerpoint Dr Suite 1400, Anchorage, AK 99503 Northstar Field/Northstar Oil Pool & Hooligan (Kuparuk) Oil Pools -11,100' TVDss/-9000' TVDss 0.75 3. Unit or Lease Name: 4. Field and Pool: 5. Datum Reference: Page 4 2024 Production Allocation Method A well’s theoretical production is calculated using metered field volumes and hours on production as follows: Gas Allocation Gross Produced Gas = total return metered at test separator. Net Produced Gas = Gross Produced Gas – Gaslift Gas. Theoretical Produced Gas = all well tests Net Produced Gas prorated by the month. (Proration calculation will include adjustments for shut in or downtime periods) Field Gas Injection = metered prior to injection Total Net Produced Gas = Field Gas Injection + Fuel Gas + Flare Gas + PPA Gas - Buy Gas (Buy Gas = imported or Caribou Crossing acquired gas). 𝑇𝑜𝑡𝑎𝑙 𝑁𝑒𝑡 𝑃𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝐺𝑎𝑠 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑃𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝐺𝑎𝑠=𝐺𝑎𝑠 𝐴𝑙𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟 Gas Allocation Factor x Theoretical Produced Gas (individual well) = Allocated Gas (individual well). Oil Allocation Actual Field Oil Production = oil volume metered by LACT (sold/delivered to Northstar crude oil pipeline) (Adjusted for BS&W, temperature, and API gravity in accordance with API standards and BSEE regulations.) Gross Produced Oil = total return metered at test separator. Theoretical Well Oil Production = all well tests Gross Produced Oil prorated by the month. (Proration calculation will include adjustments for shut in or downtime periods) Theoretical Field Oil Production = Sum of Theoretical Well Oil Production Field Natural Gas Liquid (NGL) Production = metered prior to commingling with oil 𝐴𝑐𝑡𝑢𝑎𝑙 𝐹𝑖𝑒𝑙𝑑 𝑂𝑖𝑙 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛+𝐹𝑖𝑒𝑙𝑑 𝑁𝐺𝐿 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝐹𝑖𝑒𝑙𝑑 𝑂𝑖𝑙 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛=𝑂𝑖𝑙 𝐴𝑙𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟 Oil Allocation Factor x Theoretical Well Oil Production = Allocated Oil Production (individual well). Water Allocation Actual Field Water Production = water volume metered prior to injection disposal Net Field Water Production = Actual Field Water Production – Metered Grey Water Gross Produced Water = total metered at test separator. Theoretical Well Water Production = all well tests Gross Produced Water prorated by the month. (Proration calculation will include adjustments for shut in or downtime periods) Theoretical Field Water Production = Sum of Theoretical Well Water Production 𝑁𝑒𝑡 𝐹𝑖𝑒𝑙𝑑 𝑊𝑎𝑡𝑒𝑟 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝐹𝑖𝑒𝑙𝑑 𝑊𝑎𝑡𝑒𝑟 𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛=𝑊𝑎𝑡𝑒𝑟 𝐴𝑙𝑙𝑜𝑐𝑎𝑡𝑖𝑜𝑛 𝐹𝑎𝑐𝑡𝑜𝑟 Water Allocation Factor x Theoretical Well Water Production = Allocated Water Production (individual well). Page 5 F. & G. Future Development Plans & Review of Annual Plan of Operations and Development In 2024, Hilcorp continued to maintained unit production through optimization opportunities. The field study of the Northstar Unit continued. Well histories, production and injection data, material balance calculations, geological, and geophysical work were studied and updated as necessary. The primary focus for the Northstar Ivishak development involved restoring a voidage replacement balance greater than or equal to 1.0. This was accomplished by decreasing gas injection into the Kuparuk formation and diverting gas to the Ivishak. To help offset the decreased injection in the Kuparuk, a water injection project was initiated. Projects executed during the 2024 calendar year:  NS-24 (Ivishak) – Convert to Ivishak gas injection (failed MITT, inoperable well) Projects planned for the 2025 calendar year: In 2025, Hilcorp will pursue increased unit production through additional well intervention projects, any necessary infrastructure and facility repairs, and other optimization opportunities as they arise. No drilling activities are planned at Northstar within the 2025 calendar year. Hilcorp will continue update the full field study of the Northstar Unit. This may include re-mapping productive horizons, updating well histories, reviewing production and injection data, material balance calculations, and reviewing results of any recent well intervention projects. Sincerely, Gavin Dittman Reservoir Engineer - Northstar