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Home My WebLink About2024 Oooguruk-Torok Oil Pool2024 Annual Reservoir Surveillance Report Oooguruk-Torok Oil Pool (OTOP) Oooguruk Field April 17th, 2025 Hilcorp Alaska – WNS Asset Team Table of Contents SUBJECT PAGE 1.0 Progress of the Enhanced Recovery Project ............................................................................1 2.0 Results and Analysis of Reservoir Pressure Surveys within the Pool .........................................2 3.0 Results and Analysis of Production and Injection Log Surveys, Tracer Surveys, Observation Well Surveys and Any Other Special Monitoring ......................................................................................2 4.0 Review of Pool Production Allocation Factors and Issues Over the Year ...................................2 5.0 Reservoir Management Summary .........................................................................................3 ATTACHMENT A: OTOP Well Location Map ...................................................................................4 ATTACHMENT B: 2024 OTOP Voidage Balance by Month ...............................................................5 ATTACHMENT C: 2024 OTOP Form 10-412 Pressure Report ............................................................6 ATTACHMENT D: OTOP Form 10-428 Annual Reservoir Properties Report ........................................6 Hilcorp Alaska – WNS Asset Team Page | 1 1.0 Progress of the Enhanced Recovery Project The Oooguruk Field (OF) is an offshore development on the North Slope of Alaska. Three oil pools, the Torok, Kuparuk and Nuiqsut, are currently under development within the OF. The development consists of an offshore man-made gravel island, the Oooguruk Drill Site (ODS), located just east of the Colville River Delta in Harrison Bay. ODS production is delivered to the Oooguruk Tie-in Pad (OTP) via a buried subsea flowline bundle and onshore flowlines, metered, and then transferred to Kuparuk River Unit (KRU) facilities, operated by ConocoPhillips Alaska, Inc. (CPAI), for final processing and transportation to the sales line. The current OTOP development consists of two producing wells, ODST-39 and ODST-45A, and one injection well, ODST-46i. Attachment A shows the locations of the existing OTOP wells, the OTOP area, the current OU, and the Oooguruk Torok Participating Area (OTPA). Operations included general maintenance and replacing critical oil, water, and gas piping and valves. Field-wide maintenance was also performed, including mechanical integrity inspections of piping, tanks, pressure vessels and other safety systems. As per vendor recommendation, routine maintenance was performed on the three power generation turbines, including the generator cleaning. In addition, cathodic protection inspections were completed on the sub-sea production flowline from ODS to OTP to ensure the mechanical integrity of the pipelines. The river overflood inspections are completed annually to verify the depth of cover over the buried subsea pipelines, including modeling of water flows over the ice, strudel and scour identification and bathymetric surveys. A conversion from the existing Siemens PCS7 Distributed Control System (DCS) to Emerson DeltaV is ongoing and will be completed in 2025. The Oooguruk development originally envisioned producing wells with electrical submersible pumps (ESPs) to maximize drawdown and minimize gas lift and the associated KRU and hydraulic back-out effects. Currently, most ODS producing wells require gas lift to produce; only two wells, ODSN-04 and ODSN-25, produce using ESPs. The gas lift gas coupled with the formation gas significantly impacts the flowline pressure, reducing overall flow rates and generating significant back-out costs at KRU, which is also primarily constrained by gas processing capacity. In 2024 the activity on Torok wells on ODS was limited to 1 rigless intervention on 1 well, as per Table 1 below. Table 1: 2024 OTOP Well Interventions Action #Well Name Type Location Reservoir Action Objectives Completion Date 1 ODSDW1-44 DSP ODS Torok Rigless Integrity Testing 1/28/2024 Hilcorp Alaska – WNS Asset Team Page | 2 2.0 Results and Analysis of Reservoir Pressure Surveys within the Pool Three pressure surveys were reported from three OTOP wells during 2024. Refer to Attachment D for the reported pressures surveys and relevant data. 3.0 Results and Analysis of Production and Injection Log Surveys, Tracer Surveys, Observation Well Surveys and Any Other Special Monitoring Extended shut-in bottom hole pressure data from ODST-39, ODST-45A fall-off data from ODST- 46i indicate local communication in the reservoir as evidenced by the equalization of the pressures over time (refer to Attachment C). No additional surveillance logging or surveys were conducted in 2024. 4.0 Review of Pool Production Allocation Factors and Issues Over the Year Production from the Oooguruk-Torok Oil Pool (OTOP), Oooguruk-Kuparuk Oil Pool (OKOP) and Oooguruk-Nuiqsut Oil Pool (ONOP) is commingled at the surface into a common production line. Allocation between the pools is based on the ratio of total production for a pool to the total production for the Oooguruk Unit. The pool oil allocation factors for 2024 are: ONOP:96.1% OKOP: 3.9% OTOP: 0% Theoretical production for individual wells for all pools is calculated daily. Daily theoretical production for a well was calculated using the data from the most current well test and the amount of time a well was on production for a given day: oductionlDailyTheoreticaBOPDxDailyRate dayMinutes Minutes Welltest produced Pr)( 1440  The daily allocation factor for the unit is calculated by dividing the total production for the day by the sum of the theoretical daily production for each well. Daily allocated production is assigned to each well by multiplying its theoretical daily production by the daily allocation factor. The average daily oil allocation factor for 2024 during Hilcorp operation was 0.914. Hilcorp Alaska – WNS Asset Team Page | 3 5.0 Reservoir Management Summary The AOGCC issued pool rules under Conservation Orders No. 645A, 596 and 597 for the OTOP, OKOP and ONOP, respectively. At the same time, there is no subsurface commingling; unitized substances produced from the three oil pools are commingled on the surface. Area injection orders (AIOs) authorizing the injection of fluids for enhanced oil recovery in the OTOP, OKOP, and ONOP reservoirs were issued by the AOGCC as AIO No. 37A, 33 and 34, respectively. Injection commenced into the OTOP in 2012. The OTOP reservoir management targets maximizing oil production, managing producing gas oil ratios (GOR) and maximizing long-term reservoir performance and value through enhanced recovery while minimizing the project risks and maintaining the highest environmental and safety standards. Flood throughput and reliable water supply are critical to long-term OTOP recovery. Consequently, Eni implemented SWIS in 2020 and 2021 to avoid injecting KRU-produced water, improve water supply reliability, and increase available injection pressures. SWIS uptime has been very high, successfully meeting reservoir injection targets and increasing supply pressure. The AOGCC has approved increasing the pressure limit to 3,700 psi from 2,800 psi for both the ONOP and OKOP; however, the OTOP limit currently remains at 2,800 psi consistent with Rule 4 of AIO 37A. The Annual Reservoir Properties Report (Form 10-428) is included in Attachment E. ATTACHMENT A: OTOP Well Location Map ATTACHMENT B: 2024 OTOP Voidage Balance by Month ATTACHMENT C: 2024 OTOP Form 10-412 Pressure Report ATTACHMENT D: OTOP Form 10-428 Annual Reservoir Properties Report