Department of Commerce, Community, and Economic Development
Alaska Oil and Gas Conservation Commission
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HomeMy WebLinkAbout2020 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, 2021
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,
2020 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 2020 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 2020, 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 5,579 bopd and average daily gas injection was 365 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 2020, gas injection was calculated to be 1,743 thousand-reservoir barrels (MRB) less than reservoir voidage.
At year end, the reservoir overall cumulative voidage replacement ratio was 1.07. The average of reservoir pressure
control for 2019 was 5,333 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 2020.
Page 2
B.Voidage Balance by Month of Produced Fluid and Injected Fluids – 2020
As of 12/31/2020 Full year (1)As of Dec-20 (2)
Producers 12 12
Injectors 7 7
2020
Cumulative Start-
Up through
12/31/20
2,042,069 176,328,907
133,601,771 2,755,572,212
1,961,546 71,503,377
4,841,106 79,660,591
136,341,085 3,100,691,322
94,455 2,068,590
92,712 2,204,624
-1,743 136,034
5,579
365,032
5,359
13,227
372,517
5,333 psiaAverage of surveys obtained in 2020
Water, BWPD
Injection
Water, BWPD
Gas, MCFPD
AVERAGE RESERVOIR PRESSURE
DAILY AVERAGE RATE DATA 2020
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 which contributed to production/injection during the respective year
(2) Active wells as of December 2020
PRODUCTION/INJECTION STATISTICS
Production
Table 1: NORTHSTAR FIELD 2020 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 2020 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-2020 452 7,913 189 8,555 8,555 1,982,690 9,841 0 9,841 9,841 2,121,753 1,286 1,286 139,063
Feb-2020 408 7,197 171 7,777 16,331 1,990,467 8,813 0 8,813 18,654 2,130,567 1,037 2,323 140,100
Mar-2020 423 7,876 186 8,485 24,817 1,998,952 8,058 0 8,058 26,712 2,138,625 -427 1,896 139,673
Apr-2020 386 7,490 179 8,055 32,872 2,007,007 7,645 0 7,645 34,357 2,146,269 -410 1,486 139,262
May-2020 368 7,298 170 7,837 40,709 2,014,844 7,241 0 7,241 41,599 2,153,511 -596 890 138,667
Jun-2020 342 6,337 167 6,846 47,555 2,021,690 6,745 0 6,745 48,344 2,160,256 -101 789 138,566
Jul-2020 399 6,642 166 7,207 54,762 2,028,897 7,175 0 7,175 55,519 2,167,431 -32 757 138,534
Aug-2020 390 6,629 171 7,190 61,952 2,036,087 7,024 0 7,024 62,543 2,174,455 -166 592 138,368
Sep-2020 376 6,607 164 7,147 69,099 2,043,234 6,908 0 6,908 69,451 2,181,363 -239 352 138,129
Oct-2020 405 7,086 162 7,653 76,752 2,050,887 7,164 0 7,164 76,615 2,188,527 -490 -138 137,639
Nov-2020 291 7,523 163 7,976 84,728 2,058,863 7,694 0 7,694 84,309 2,196,221 -282 -419 137,358
Dec-2020 331 9,220 177 9,727 94,455 2,068,590 8,403 0 8,403 92,712 2,204,624 -1,324 -1,743 136,034
2020 Totals 4,572 87,818 2,066 94,455 92,712 0 92,712 -1,743
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-06 50029230880000 O 590100 Ivishak 10,873'-11,162'7/19/20 1584 SBHP 255 11,100 5,301 11,100 0.19 5,301
NS-07 50029230810000 O 590150 Kuparuk 9,002'-9,022'10/22/20 66 PBU 187 8,726 2,458 9,000 0.09 2,483
NS-12 50029230910000 O 590100 Ivishak 10,995'-11,077'10/23/20 72 SBHP 252 11,000 5,246 11,100 0.09 5,256
NS-13 50029230170000 O 590150 Kuparuk 8,875'-9,000'10/9/20 116 PBU 175 8,485 2,302 9,000 0.09 2,348
NS-14A 50029230260100 O 590100 Ivishak 10,893'-11,082'10/14/20 360 SBHP 254 11,000 5,327 11,100 0.09 5,336
NS-16A 50029230960100 O 590100 Ivishak 11,034'-11,108'7/20/20 96 SBHP 254 11,100 5,358 11,100 0.10 5,358
NS-19 50029231220000 O 590100 Ivishak 10,954'-11,069'10/13/20 13,800 SBHP 253 10,900 5,216 11,100 0.10 5,339
NS-20 50029231180000 O 590100 Ivishak 10,932'-11,030'4/22/20 8928 SBHP 250 11,000 5,369 11,100 0.09 5,379
NS-21 50029231260000 O 590100 Ivishak 11,012'-11,099'4/23/20 72 SBHP 250 11,000 5,355 11,100 0.10 5,365
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 knowledge.
Signature
Printed Name
Title
Date
Reservoir Engineer
January 15, 2021
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
2019 is 5,333 psia, down 84 psia from the 2019 average; this is due to increasing Kuparuk gas injection in 2020 with
the NS-17 recomplete to the Kuparuk zone.
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 2020.
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.
2020 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 1.56 for oil, 0.75 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 2020, 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 2020 calendar year:
·NS-17 (Injector)- Performed RWO recompletion from the Ivishak reservoir gas injector to a lean gas injection
well in the Kuparuk C reservoir. (October 2019 RWO executed, February 2020 initial put on injection)
·Completed the Northstar Propane Chiller Project. Activities included construction of an ice road, installing
support frames, setting chiller modules, and installing associated chiller system piping (June 2020)
·NS-25 (Producer)– Performed RWO to install SCSSV (surface controlled subsurface safety valve) to increase
production (October 2020)
·NS-05 (Producer) – Add Perforations (March 2020)
·NS-11 (Producer) – Add Perforations (March 2020)
Projects planned for the 2021 calendar year:
In 2021, 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 2021 calendar year.
Expansion of the existing ground refrigeration system is planned. This will include drilling new heat pipes,
modifying existing thermosiphons to use active refrigeration, and installing a brine heat exchanger at the existing
refrigeration unit.
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,
Joleen Oshiro
Reservoir Engineer - Northstar
