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Home My WebLink About2023 Oooguruk-Nuiqsut Oil Pool 2023 Annual Reservoir Surveillance Report Oooguruk-Nuiqsut Oil Pool (ONOP) Oooguruk Field April 1, 2024 Eni Petroleum, Alaska 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 .......................................... 4 3.0 Results and Analysis of Production and Injection Log Surveys, Tracer Surveys, Observation Well Surveys and Any Other Special Monitoring ....................................................................................... 4 4.0 Review of Pool Production Allocation Factors and Issues Over the Year .................................... 5 5.0 Reservoir Management Summary........................................................................................... 6 ATTACHMENT A ONOP Well Location Map .................................................................................... 8 ATTACHMENT B 2023 ONOP Voidage Balance by Month ................................................................ 9 ATTACHMENT C ONOP Pressure Report, Form 10-412 .................................................................. 10 ATTACHMENT D ONOP Reservoir Pressure Map – December, 2023 ............................................... 11 ATTACHMENT E ONOP Annual Reservoir Properties Report, Form 10-428 ...................................... 12 Eni Petroleum, Alaska Page 1 1.0 Progress of the Enhanced Recovery Project The Oooguruk Field (OF) is one of two Eni US Operating Co. Inc. (Eni) offshore-operated fields in 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, then transferred to Kuparuk River Unit (KRU) facilities, operated by ConocoPhillips Alaska, Inc. (CPAI), for final processing and transportation to the sales line. At the end of 2023, there were 28 active Oooguruk-Nuiqsut Oil Pool (ONOP) development wells, including 18 producer and ten injection wells. One producing well, ODSN-06 Nuiqsut, remains shut-in as it is isolated in the ODSN-06 wellbore to allow production from the Kuparuk interval. Commingling is not currently allowed nor functional at this time. The locations of the ONOP, the existing and planned ONOP wells, the current OU, and Oooguruk Nuiqsut Participating Area (ONPA) are shown in Attachment A. During 2023, Operations and Facilities engineering performed internal operations and maintenance assessments to ensure compliance with corporate requirements. Eni’s corporate operations team also conducted a Oooguruk asset review to identify bottlenecks at the plant, efficiencies, and production improvement opportunities. The 2023 asset review recommended detailed actions and an engineering study to be conducted in cooperation with the specialists at HQ. An internal corporate assessment was also performed to ensure compliance with internal procedures on safety and environmental critical elements. An engineering study was conducted to revamp the 2-phase separator. 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 detailed monitoring plan for injection system microbes was established with systematic biocide treatments conducted during 2023. Capital projects included eight (8) well workovers, 7 producers, and 1 injector. Four (4) ESPs were installed in production wells. The OTP control room design study was completed to relocate the OTP control room in 2025. Capital projects included upgrading the Fire and Gas software, mandatory tank and vessel inspections, lift/injection compressor PLC upgrade and module lifecycle upgrade. The ODS exterior camera system was completed and upgraded in 2023 to allow Eni Petroleum, Alaska Page 2 enhanced warning of nearby polar bears, seawater injection line pig trap upgrades, and the addition of a corrosion coupon to the ODS subsea diesel flowline was also completed. A conversion from the existing Siemens PCS7 Distributed Control System (DCS) to Emerson DeltaV has been developed, with a detailed engineering study supporting implementation during the 2025 planned major maintenance turnaround. Finally, the Rig Support Complex (RSC) has been partially revamped to support the Well Work Over campaign that took place and future drilling campaigns. The revamping will continue in the following years. The Oooguruk development originally envisioned producing wells would ultimately utilize electrical submersible pumps (ESPs) in order to maximize drawdown and minimize gas lift and the associated KRU and hydraulic back-out effects. Currently, the majority of the OF 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 OF formation gas significantly impacts the flowline pressure, reducing overall flowrates, and generates significant back-out cost at KRU, which is also primarily constrained by gas processing capacity. These constraints result in backing out KRU fluid production when high total gas oil ratio (TGOR, includes formation and lift gas) OF fluids enter the system. Because of the hydraulic effects and KRU back-out all OF wells cannot be produced concurrently using gas lift. In 2023, on average, 14 of the 22 available producing OF wells were on-line with TGOR ranking typically used to determine which wells to produce. In 2023, the workover campaign started in 2022 was concluded with the replacement of the completion on ODSN-10i due to a stuck TRSCSSSV (started in December 2022) and with two ESP replacements on ODSN-02 and ODSN-04. Table 1 below, summarizes the ONOP RWO and rigless (RLWO) interventions completed in 2022. Nabors rig was put in cold stack in March 2023. Eni Petroleum, Alaska Page 3 Table 1: 2023 ONOP Well Interventions As a result of the May 2022 thru March 2023 rig program and sustained water injection, OF oil production peaked in April 2023 at 7,488 bpd from 5,000 bpd in April 2022, an increase of 2,488 bpd (+50%). December 2023 OF oil production averaged 6,217 bpd; the 1,271-bpd decline ( 17%) from April was primarily a result of two early ESP failures (ODSN-02 in May and ODSK-41 in August), ODSN 06 Kuparuk oil rate decline, which was as expected, and overall OF decline. The 2023 annual average daily oil rate was 6,650 bpd, up 10% from 6,030 bpd in 2022. Produced water averaged 3,428 bpd, a 34% watercut, in 2023 up slightly from 3,280 bpd, a 35% watercut, in 2022. Total OF gas rates, formation plus lift gas, remained relatively stable averaging 20.5 MMSCFPD in 2023 compared to 21.4 MMSCFPD in 2022. The OF production network remains hydraulically constrained so only 13 of the 22 available wells were on-line on December 31, 2023. Annual average daily ONOP oil production for 2023 was 5,689 BOPD, 85.5% of OF production. Total ONOP oil production during 2023 was 2,076,520 barrels for a cumulative 37,886,770 barrels since field start-up in 2008. The 2023 annual average producing gas oil ratio (GOR) and watercut were 732 SCF/STBO and 26%, respectively. The December 2023 average GOR was 657 SCF/STBO and the watercut was 21%. Average annual daily water injection for 2023 was 9,192 bpd. Total water injection in 2023 was 3,355,189 barrels for a cumulative 38,510,040 barrels since the start of injection in 2009. The December 2023 average injection rate was 9,418 bpd. No gas injection occurred in 2023. Cumulative gas injection in the ONOP is 12,617 MMSCF since the start of the project. The annual voidage replacement ratio averaged 77% for the year. The cumulative voidage replacement ratio is at 57%. Attachment B details the 2023 voidage balance for the ONOP. Action #Well Name Well Type Location Reservoir Action Type Objectives / Description Completion date 1 ODSN-10i OP ODS Nuiqsut RWO Remove stuck TRSCSSSV 1/10/2023 2 ODSN-02 OP ODS Nuiqsut RWO Replace ESP 2/7/2023 3 ODSN-06i OP ODS Nuiqsut Rigless Inflow test on TRSCSSSV 2/18/2023 4 ODSN-04 OP ODS Nuiqsut RWO Replace ESP 3/12/2023 5 ODSN-25 OP ODS Nuiqsut Rigless Inflow test 2/19/2023 6 ODSN-16 OP ODS Nuiqsut Rigless Troubleshoot TRSCSSSV 2/19/2023 7 ODSN-10i WI ODS Nuiqsut Rigless Orifice Valve change out 3/12/2023 8 ODSN-40 OP ODS Nuiqsut Rigless SSSV test 3/9/2023 9 ODSN-31 OP ODS Nuiqsut Rigless Discharge Head fill cleanout 4/9/2023 10 ODSN-31 OP ODS Nuiqsut Rigless Discharge Head fill cleanout 5/28/2023 11 ODSN-24 OP ODS Nuiqsut Rigless Replace WLRSSSV 5/14/2023 12 ODSN-27i WI ODS Nuiqsut Rigless SSSV service 6/15/2023 Eni Petroleum, Alaska Page 4 2.0 Results and Analysis of Reservoir Pressure Surveys within the Pool Seven pressure surveys recorded in 2023 were reported from six wells. The pressure survey results are summarized in the ONOP Pressure Report, Form 10-412 (See Attachment C). The ONOP Reservoir Pressure Map, Attachment D, depicts the estimated ONOP average pressures for December 2023 including all wells, both shut-in and on-line. The estimated average ONOP December 2023 reservoir pressure is 2,450 psi at 6,350 ft. TVDss. The 2023 average annual producing GOR was 732 SCF/STBO and in December 2023 the GOR averaged 657 SCF/STBO consistent with sustained water injection voidage replacement (See Attachment E, Nuiqsut Annual Reservoir Properties Report Form 10-428). 3.0 Results and Analysis of Production and Injection Log Surveys, Tracer Surveys, Observation Well Surveys and Any Other Special Monitoring Reservoir surveillance is routinely conducted to monitor wells and reservoir performance and to recommend changes in operating conditions, perform rate allocations, propose optimization actions, address, and solve general issues. Historically well surveillance equipment was placed in the liners of seventeen Nuiqsut wells during the initial completions. The systems are in-place to assess production profiles and continuity along the lateral via target fluid tracers, which were monitored and analyzed by collecting surface fluid samples during restarts and over time. The tracers have been used to assess hydraulic connectivity along the laterals to evaluate the need for coil tubing interventions to clear any sand or debris blocking the flow path. For all wells the oil tracer components are no longer active. However, if a significant water breakthrough event occurs sampling to assess the water tracer response is planned. Scoping of an interwell tracer survey was initiated in 2023; the objective of the study would be to quantify breakthrough times and sweep efficiency in several patterns. Eni Petroleum, Alaska Page 5 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 2023 are: ONOP: 85.5% OKOP: 14.3% OTOP: 0.2% Theoretical production for individual wells for all pools is calculated on a daily basis. During 2023 wells were produced with chokes at 100% most of the time due to the capacity of the production line. 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 actual total production for the day by the sum of the theoretical daily production for each individual well. Daily allocated production is assigned to each well by multiplying its theoretical daily production by the daily allocation factor. The average daily allocation factor for 2023 was 0.9246. Eni Petroleum, Alaska Page 6 5.0 Reservoir Management Summary The AOGCC issued pool rules under Conservation Orders No. 645A, 596 and 597 for the OTOP, OKOP and the ONOP, respectively. While 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 ONOP in 2009. During 2023 the ONOP Under-Saturated Water-Alternating-Gas (US-WAG) reservoir management included maximizing voidage replacement, while minimizing known adverse injector to producer flow path connections and managing producing gas oil ratios by cycling producing wells on and off production where possible operationally. The current cumulative voidage replacement ratio is at 57%, which is consistent with ratio of injection wells to producing wells (17 producer and ten injection wells active) and the overall ONOP pattern layout. Attachment B details the 2023 annual and cumulative voidage balance for the ONOP. In general, producing wells in the more mature flood areas have seen GOR stabilization, stabilized or increased oil production, and some water breakthrough as expected, and also via unexpected connections which are being evaluated, monitored and managed. With the consistent water injection and ample supply due to implementation of SWIS, ONOP flood throughput has increased reducing the overall GOR and stabilizing area pressures. Following the July 2019 water injection shut-in, the ONOP average monthly GOR peaked in September 2020 at 1,435 SCF/STBO from a low of 675 SCF/STBO in October 2019 and has since declined to 657 SCF/STBO in December 2023. Similarly, ONOP average monthly watercut decreased from 20% in August 2019 to 10% in January 2021 and has since stabilized at 21% in December 2023. Overall ONOP pressures have stabilized and in some areas are increasing. The central Kalubik fault block (Kalubik) currently has 11 wells, seven producers and four injectors. Kalubik 2023 average daily production was 1,876 BOPD, 33% of ONOP production, with 755 BWPD (29% water cut) at a 777 SCF/STBO GOR. Four producers were produced consistently during 2023 with uptime greater than 80%: ODSN-01A (90%), ODSN-25 (99%), ODSN-31 (83%), and ODSN-37 (98%). Two producers were cycled to manage voidage replacement and maximize production given the OF hydraulic constraints: ODSN-36 (54%) and ODSN-42B (52%). The ODSN-24 well had very limited production (9% uptime) due to its high TGOR. Water injection was sustained throughout 2023 in up dip injectors ODSN-19 and ODSN-26 at moderate pressures to provide pressure support and improve recovery in offset producers while also minimizing known flow path connections. Injection in the central wells ODSN-32 and ODSN-34 was also sustained throughout 2023 at higher pressures while monitoring for any connections (none are known to date), thus increasing cumulative VRR, and supporting central and up-dip Kalubik wells. The Kalubik 2023 annual average daily water injection rate was 3,028 BPD; gas was not injected during 2023. Eni Petroleum, Alaska Page 7 The southern Colville Delta and Southwest Extended Reach Drilling (ERD) fault block area (CD-ERD) currently has nine wells, six producers and three injectors. CD-ERD 2023 average daily production was 2,119 BOPD, 37% of ONOP production, with 486 BWPD (19% water cut) at a 819 SCF/STBO GOR. Four producers were produced consistently during 2023 with uptime greater than 80%: ODSN-10 (81%), ODSN-16 (98%), ODSN-22 (99%), and ODSN-43 (98%). One producer, ODSN-18 was cycled (45% uptime) to manage voidage replacement and maximize production given the OF hydraulic constraints. ODSN-17 has essentially been shut-in since October 2021 due to a failed SSSV; several interventions were conducted in 2022 and 2023 to repair the valve, but its function has not been restored; the well remains shut-in and secured. Water injection was sustained throughout 2023 in ODSN-15 and ODSN-23; injection in ODSN-48 was shut-in from March 23, 2023 to May 24, 2023 due to a strong water flow path connection impacting production in ODSN-22; the shut-in allowed ODSN-22 water production to clean-up and ODSN-48 injection has been sustained at lower pressures and rates. The CD-ERD 2023 annual average daily water injection rate was 2,642 BPD; gas was not injected in the CD-ERD injectors during 2023. The Ivik fault block (Ivik) currently has eight wells, five producers and three injectors. Ivik 2023 average daily oil production was 1,695 BOPD, 30% of ONOP production, with 575 BWPD (31% watercut) at a 575 SCF/STBO GOR. Three producers were produced consistently during 2023 with uptime of at least 80%: ODSN-04 (80%), ODSN-28 (99%), and ODSN-29 (98%). ODSN-02 produced consistently with an ESP until May 7, 2023, when it failed; initially, back-up gas lift was used to lift the well; however, due to its non-competitive TGOR on back-up gas lift the well was shut-in on June 8, 2023, and remains shut-in. In 2022 Kuparuk offtake was moved more distal from the ODSN-29 wellbore to the ODSN-06 wellbore to improve recovery from both pools. Consequently, ODSN-06 Nuiqsut remains shut-in; the Nuiqsut in the well is isolated and commingling is not currently allowed nor functional at this time. Concurrently, after isolating the Kuparuk in the ODSN-29 wellbore, the lower Nuiqsut completion was reopened, and production restarted in November 2022. Water injection was sustained throughout 2023 in ODSN-03, ODSN-07, and ODSN-27 with periodic rate adjustments to manage voidage replacement and known water flow path connections during producer shut-ins. The Ivik 2023 annual average daily water injection rate was 3,523 BPD; gas was not injected in the Ivik injectors during 2023. Individual well and pattern surveillance data will continue to be collected to monitor performance and improve recovery. A simulation model has been maintained and updated to assist in reservoir development and flood management decisions in the ONOP. Eni Petroleum, Alaska Page 8 ATTACHMENT A ONOP Well Location Map Eni Petroleum, Alaska Page 9 ATTACHMENT B 2023 ONOP Voidage Balance by Month Month Oil, MRB Free Gas, MRB Water, MRB Total Voidage, MRB Year Cum, MRB Cum since start-up, MRB Gas, MRB Water, MRB Total Injection, MRB Year Cum, MRB Cum. since start-up, MRB Net Injection, MRB Year Cum, MRB Cum since start-up, MRB Cum Since Start-Up thru 2022>>80,821 Cum Since Start-Up thru 2022 >>45,076 -35,745 Jan-23 189 95 64 347 347 81,169 0 345 345 345 45,422 -2 -2 -35,747 Feb-23 169 102 69 340 687 81,508 0 300 300 646 45,722 -39 -41 -35,786 Mar-23 202 116 99 417 1,104 81,926 0 321 321 966 46,042 -97 -138 -35,883 Apr-23 215 137 93 445 1,549 82,371 0 267 267 1,233 46,309 -178 -316 -36,061 May-23 214 155 70 439 1,988 82,810 0 271 271 1,504 46,580 -169 -485 -36,230 Jun-23 197 118 50 365 2,353 83,175 0 256 256 1,759 46,835 -109 -594 -36,339 Jul-23 198 114 56 369 2,722 83,543 0 282 282 2,042 47,118 -86 -680 -36,426 Aug-23 181 100 44 325 3,047 83,868 0 212 212 2,254 47,330 -113 -793 -36,538 Sep-23 206 99 48 353 3,400 84,221 0 266 266 2,520 47,596 -87 -880 -36,625 Oct-23 209 85 49 343 3,743 84,564 0 284 284 2,804 47,880 -59 -939 -36,684 Nov-23 187 71 46 304 4,047 84,869 0 259 259 3,063 48,140 -45 -984 -36,729 Dec-23 200 90 47 337 4,384 85,206 0 292 292 3,355 48,431 -45 -1,029 -36,774 2023 Totals 2,367 1,282 735 4,384 0 3,355 3,355 -1,029 Produced Fluids Injected Fluids Net Injection Eni Petroleum, Alaska Page 10 ATTACHMENT C ONOP Pressure Report, Form 10-412 6. Oil Gravity: 19 -25 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) ODSN-01A 50703206480100 O 576150 Nuiqsut 6154 - 6232 6/27/2023 728 PBU 164 5,989 1,432 6,350 0.40 1,576 ODSN-02 50703206220000 O 576150 Nuiqsut 6226 - 6190 2/4/2023 301 SBHP 138 6,135 1,834 6,350 0.45 1,930 ODSN-04 50703206700000 O 576150 Nuiqsut 6339 - 6307 3/12/2023 6,189 SBHP 145 5,936 1,778 6,350 0.45 1,963 ODSN-31 50703205650000 O 576150 Nuiqsut 6074 - 6263 5/24/2023 439 SBHP 164 5,749 2,222 6,350 0.40 2,462 ODSN-42B 50703206050200 O 576150 Nuiqsut 6282 - 6466 4/28/2023 3,737 PBU 171 6,234 1,406 6,350 0.38 1,450 ODSN-42B 50703206050200 O 576150 Nuiqsut 6282 - 6466 12/15/2023 823 PBU 171 6,234 1,159 6,350 0.38 1,203 ODSN-48 50703206790000 WAG 576150 Nuiqsut 6004 - 6165 5/24/2023 1,486 PFO 138 5,851 3,925 6,350 0.45 4,147 Eni US Operating Company Inc. (Eni US)3700 Centerpoint Drive, Suite 500, Anchorage, AK 99503 STATE OF ALASKA ALASKA OIL AND GAS CONSERVATION COMMISSION RESERVOIR PRESSURE REPORT 1. Operator:2. Address: 3. Unit or Lease Name:4. Field and Pool:5. Datum Reference:7. Gas Gravity: Oooguruk Oooguruk-Nuiqsut 6350 0.7 Printed Name Keith Lopez Date April 1, 2024 23. All tests reported herein were made in accordance with 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. Signature Title Production Engineer Eni Petroleum, Alaska Page 11 ATTACHMENT D ONOP Reservoir Pressure Map – December, 2023 Eni Petroleum, Alaska Page 12 ATTACHMENT E ONOP Annual Reservoir Properties Report, Form 10-428 3. Field and Pool Code: 4. Pool Name 5. Reference Datum (ft TVDSS) 6. Temperature (°F) 7. Porosity (%) 8. Permeability (md) 9. Swi (%)10. Oil Viscosity @ Original Pressure (cp) 11. Oil Viscosity @ Saturation Pressure (cp) 12. Original Pressure (psi) 13. Bubble Point or Dew Point Pressure (psi) 14. Current Reservoir Pressure (psi) 15. Oil Gravity (°API) 16. Gas Specific Gravity (Air = 1.0) 17. Gross Pay (ft) 18. Net Pay (ft) 19. Original Formation Volume Factor (RB/STB) 20. Bubble Point Formation Volume Factor (RB/STB) 21. Gas Compressibility Factor (Z) 22. Original GOR (SCF/STB) 23. Current GOR (SCF/STB) 576150 Nuiqsut 6350 170 2 - 20 1 - 50 30 -60 3 - 7 3 - 7 3250 1900 2450 19 - 25 0.7 80 - 170 40 - 110 1.15 1.14 0.7 250 - 400 657 Production Engineer STATE OF ALASKA ALASKA OIL AND GAS CONSERVATION COMMISSION ANNUAL RESERVOIR PROPERTIES REPORT 1. Operator:2. Address: Eni US Operating Company Inc. (Eni US)3700 Centerpoint Drive, Suite 500, Anchorage AK 99503 4/1/2024Printed Name Keith Lopez Date I hereby certify that the foregoing is true and correct to the best of my knowledge. Signature Title