Department of Commerce, Community, and Economic Development
Alaska Oil and Gas Conservation Commission
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HomeMy WebLinkAbout2021 Northstar Oil PoolHilcorp Alaska, LLC
Post Office Box 244027
Anchorage, AK 99524-4027
3800 Centerpoint Drive
Suite 1400
Anchorage, AK 99503
Phone: 907/777-8486
Joleen.oshiro@hilcorp.com
April 1st, 2022
Jeremy Price, 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,
2021 ANNUAL RESERVOIR REVIEW
Dear Commissioner Price:
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 2021 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 2021, 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 5,610 bopd and average daily gas injection was 397 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 NS34A and Kuparuk zone production from wells NS-08, NS-13, NS-15, NS-18, and
NS-07. Kuparuk gas injection into wells NS-17 and NS-18 also excluded.
During 2021, gas injection was calculated to be 5,990 thousand-reservoir barrels (MRB) more than reservoir
voidage. At year end, the reservoir overall cumulative voidage replacement ratio was 1.06. The average of reservoir
pressure control for 2021 was 5,267 psia.
Hilcorp became the official Operator of the Northstar Field effective November 18, 2014. As a result, the historic
reservoir simulation model developed by the previous operator will no longer will be utilized. Hilcorp continued to
focus efforts on the Kuparuk reservoir simulation model during 2021.
Page 2
B.Voidage Balance by Month of Produced Fluid and Injected Fluids – 2021
As of 12/31/2021 Full year (1)As of Dec-19 (2)
Producers 15 14
Injectors 8 7
2021
Cumulative Start-
Up through
12/31/21
2,047,582 178,377,277
144,774,115 2,901,116,221
1,788,070 73,291,807
5,111,671 84,772,263
156,070,268 3,257,506,116
963,617 1,980,437
1,070,036 2,102,532
106,419 122,095
5,610
396,641
4,899
14,005
427,590
5,267 psiaAverage of surveys obtained in 2021
Water, BWPD
Injection
Water, BWPD
Gas, MCFPD
AVERAGE RESERVOIR PRESSURE
DAILY AVERAGE RATE DATA 2021
Production
Oil, BOPD
Gas, MCF/D
Gas (MCF)
Balance (excludes satellite well NS-34A and NS08 & NS-18 Kup oil Production )
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 w hich contributed to production/injection during the respective year
(2) Active wells as of December 2021
PRODUCTION/INJECTION STATISTICS
Production
Table 1: NORTHSTAR FIELD 2021 OVERVIEW STATISTICAL SUMMARY
WELL STATISTICS
NOTES:
Page 3
C.Summary and Analysis of reservoir pressure surveys within the pool
Static bottom hole pressures collected in 2021 are summarized below. Please note that the reported reservoir
pressure of the wells NS-07 and NS-13 are from the Kuparuk Reservoir.
These pressures have been included with the historical Ivishak reservoir pressure data and are graphically
represented in the next figure.
Month Oil, MRB Free Gas, MRB
Water,
MRB
Total
Voidage,
MRB
Year
Cum, MRB
Cum since
start-up, MRB
Formation
Gas,
MRB
Pilot/Purge
/Flare &
Import
Gas, MRB
Total
Injection,
MRB
Year
Cum,
MRB
Cum since
start-up,
MRB
Net
Injection,
MRB
Year
Cum,
MRB
Cum since
start-up,
MRB
Jan-2021 422 9,411 171 9,832 9,832 1,990,179 9,690 -904 8,786 8,786 2,114,154 -1,046 -1,046 123,975
Feb-2021 401 8,169 156 8,569 18,401 1,998,748 8,434 -133 8,302 17,088 2,122,456 -267 -1,313 123,708
Mar-2021 433 9,036 177 9,470 27,871 2,008,218 9,324 1,211 10,535 27,623 2,132,991 1,065 -248 124,773
Apr-2021 408 8,410 166 8,818 36,689 2,017,036 8,680 1,086 9,766 37,389 2,142,757 948 700 125,721
May-2021 371 7,349 161 7,719 44,408 2,024,755 7,594 1,272 8,866 46,255 2,151,623 1,147 1,847 126,867
Jun-2021 353 7,040 151 7,393 51,801 2,032,148 7,274 598 7,872 54,127 2,159,494 479 2,325 127,346
Jul-2021 289 5,409 126 5,698 57,499 2,037,846 5,601 163 5,763 59,890 2,165,258 65 2,391 127,411
Aug-2021 360 7,263 164 7,623 65,122 2,045,469 7,502 1,005 8,507 68,397 2,173,765 884 3,275 128,295
Sep-2021 364 7,364 149 7,727 72,850 2,053,197 7,605 923 8,528 76,925 2,182,293 801 4,075 129,096
Oct-2021 388 8,028 154 8,416 81,265 2,061,612 8,285 734 9,019 85,944 2,191,312 604 4,679 129,700
Nov-2021 389 8,614 148 9,003 90,269 2,070,616 8,872 848 9,720 95,664 2,201,032 716 5,395 130,416
Dec-2021 407 9,316 160 9,722 99,991 2,080,338 9,585 732 10,317 105,981 2,211,349 595 5,990 131,011
2021 Totals 4,584 95,407 1,883 99,991 98,446 7,535 105,981 5,990
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)psig
NS-15 50029230730000 O 590150 Kuparuk 8,940'-8,994'1/1/21 528 SBHP 175 8,900 2,929 9,000 0.10 2,936
NS-07 50029230810000 O 590150 Kuparuk 9,002'-9,022'9/10/21 36 PBU 186 8,726 2,406 9,000 0.10 2,431
NS-13 50029230170000 O 590150 Kuparuk 8,875'-9,000'7/20/21 72 PBU 175 8,485 2,264 9,000 0.10 2,310
NS-19 50029231220000 O 590100 Ivishak 10,954'-11,069'5/8/21 183,384 SBHP 250 10,900 5,186 11,100 0.10 5,207
NS-09 50029230520000 O 590100 Ivishak 10,932'-11,030'7/24/21 600 SBHP 250 10,800 5,207 11,100 0.10 5,236
NS-11 50029233030000 O 590100 Ivishak 11,044'-11,095'7/24/21 144 SBHP 250 11,054 5,217 11,100 0.10 5,222
NS-20 50029231180000 O 590100 Ivishak 10,932'-11,030'12/21/21 23,544 SBHP 250 11,000 5,289 11,100 0.10 5,300
NS-14A 50029230260100 O 590100 Ivishak 10,893'-11,082'12/23/21 72 SBHP 253 11,000 5,309 11,100 0.10 5,319
NS-16A 50029230960100 O 590100 Ivishak 11,034'-11,108'12/24/21 108 SBHP 255 11,100 5,317 11,100 0.10 5,317
Comments:
Joleen Oshiro
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 know ledge.
Signature
Printed Name
Title
Date
Operations Engineer
March 2, 2022
STATE OF ALASKA
ALASKA OIL AND GAS CONSERVATION COMMISSION
RESERVOIR PRESSURE REPORT
1. Operator:2. Address:
Hilcorp Alaska, LLC 3800 Centerpoint Dr Suite 1400, Anchorage AK 99503
7. Gas Gravity:
Northstar Unit -11,100' TVDss/-9,000' TVDss 0.75
3. Unit or Lease Name:5. Datum Reference:4. Field and Pool:
Northstar Field/ Northstar Oil Pool &
Hooligan (Kuparuk) Oil Pools
Page 4
The data shows a decrease of reservoir pressure during 2020. The average Northstar field reservoir pressure for
2021 is 5,267 psia, down 66 psia from the 2020 average. The reservoir pressure was closer to 5200psi early in the
2021 calendar year, but increased to ~5320psi by the end of the year due to increased injection into the Ivishak
reservoir.
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 2021.
The gas tracer program, initiated in 2004, was concluded in 2008 and there are no further updates for this reporting
period.
Page 5
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.
2021 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).
ܶݐ݈ܽ ܰ݁ݐ ܲݎ݀ݑܿ݁݀ ܩܽݏ
ܶℎ݁ݎ݁ݐ݈݅ܿܽ ܲݎ݀ݑܿ݁݀ ܩܽݏ =ܩܽݏ ܣ݈݈ܿܽݐ݅݊ ܨܽܿݐݎ
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
ܣܿݐݑ݈ܽ ܨ݈݅݁݀ ܱ݈݅ ܲݎ݀ݑܿݐ݅݊ +ܨ݈݅݁݀ ܰܩܮ ܲݎ݀ݑܿݐ݅݊
ܶℎ݁ݎ݁ݐ݈݅ܿܽ ܨ݈݅݁݀ ܱ݈݅ ܲݎ݀ݑܿݐ݅݊ =ܱ݈݅ ܣ݈݈ܿܽݐ݅݊ ܨܽܿݐݎ
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
ܰ݁ݐ ܨ݈݅݁݀ ܹܽݐ݁ݎ ܲݎ݀ݑܿݐ݅݊
ܶℎ݁ݎ݁ݐ݈݅ܿܽ ܨ݈݅݁݀ ܹܽݐ݁ݎ ܲݎ݀ݑܿݐ݅݊ =ܹܽݐ݁ݎ ܣ݈݈ܿܽݐ݅݊ ܨܽܿݐݎ
Water Allocation Factor x Theoretical Well Water Production =Allocated Water Production (individual well).
Northstar field allocation factors for 2020 averaged 1.26 for oil, 0.76 for water and 0.72 for gas. Oil allocation
factor was high due to allocation of NGL production. This data includes all Kuparuk producers as well.
Page 6
F. & G. Future Development Plans & Review of Annual Plan of Operations and Development
In 2021, Hilcorp continued to maintained unit production through optimization opportunities. The field study of
the Northstar Unit was continued. Well histories, production and injection data, material balance calculations,
geological, and geophysical work were studied and updated. The Ivishak reservoir simulation model, begun in
2015, was unrealistically matched to the historical Ivishak reservoir data. This project was deferred for work on
the Kuparuk reservoir model. The Ivishak model be revisited and refined for possible future development
purposes.
Projects completed during the 2021 calendar year:
·No intervention wellwork was completed in the at Northstar within the Ivishak reservoir in the 2021 calendar
year.
Projects planned for the 2022 calendar year:
In 2022, Hilcorp will pursue increased unit production through additional well intervention projects, any necessary
infrastructure and facility repairs, and other optimization opportunities as they arise. Hilcorp will also continue to
pursue the effort to import gas from Prudhoe Bay to improve Kuparuk voidage balance.
No drilling activities are planned at Northstar within the 2022 calendar year.
Gas debottlenecking in the Northstar facilities is currently under evaluation. This project would benefit Ivishak by
increasing the gas handling capacities and potentially allowing for increased production in select well.
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,
Anthony McConkey
Reservoir Engineer - Northstar
