There are three major areas at Prudhoe Bay, the state’s largest producer - the Initial Participating areas, Greater Point McIntyre and the Western Satellites.
In 2020-21 there were no wells drilled in the IPA, the oldest and most established area at Prudhoe, and few at Greater Point McIntyre.
Initially there were no wells planned for the Western Satellites - but that changed for 2021, and so far the Western Satellite area also looks to be the focus on 2022 Prudhoe drilling, with as many as 10 wells now proposed.
Prudhoe Bay operator Hilcorp North Slope told the Alaska Division of Oil and Gas in January in its proposed Western Satellites 2021 plan of development: “Due to the challenging economic conditions related to the COVID-19 global pandemic, the PBU working interest owners did not approve a drilling program for 2021.” Hilcorp said resumption of drilling in 2022 would depend on market conditions and WIO approval.
Circumstances changed.
In mid-July, Hilcorp told the division it now anticipated completing as many as six wells within the Orion Participating Area in the Western Satellites during the 2021 POD period, including up to three producers and one injector from L pad and up to one producer and one injector from Z pad.
The division approved the POD amendment July 28.
Hilcorp North Slope acquired working interest and operatorship from former operator, BP Exploration (Alaska) in the summer of 2020 via acquisition of the operator’s corporate entity.
The Prudhoe Bay WIOs are ConocoPhillips Alaska, ExxonMobil Alaska Production, Hilcorp North Slope and Chevron U.S.A.
Proposed 2022 work
Drilling proposed for the 2022 POD period, Jan. 1, 2022, through Dec. 31, 2022, includes up to 10 new wells, Hilcorp said. The company listed more than 10 candidates to be evaluated, and said the potential candidates were not limited to those named.
*Aurora PA, up to one S pad producer.
*Borealis PA, up to three L pad producers and up to one V pad injector.
*Midnight Sun PA, no planned drilling activity.
*Orion PA, up to four producers and two injectors at Z pad and up to two producers and two injectors at V pad.
*Polaris PA, up to two producers and one injector at W pad and up to one producer and one injector at M pad.
Hilcorp said it anticipates up to three workovers or recompletions during the 2022 POD, with candidates including, but not limited to:
*Aurora PA, no planned workovers or recompletes, but Hilcorp said it is “continuing to evaluate well-stock.”
*Borealis PA, as with Aurora, no workovers or recompletes planed, but continued evaluation of well stock.
*Midnight Sun PA, no planned workovers or recompletes.
*Orion PA, one rig workover to install sand control in V-205.
*Polaris PA, two rig workovers to add additional injection.
On the facilities side, Hilcorp said it is “evaluating additional sand jetting improvement projects at GC-2 in the C and D slug catchers, similar to the project executed for the B slug catcher in 2021.”
L pad expansion is also being evaluated, work which would provide space for future drilling.
The company said it “plans to continue evaluating opportunities to improve the western area gathering infrastructure.”
Long term, future drilling opportunities are being evaluated along with evaluation of potential undeveloped resources. New pad development options will be evaluated, along with polymer injection and expansion of L pad.
A reservoir engineering and geologic study of I pad development will start in the fourth quarter of 2021, with detailed pad options and facility layouts to be evaluated during the 2022 POD period, Hilcorp said.
Starting in the fourth quarter of 2021, Hilcorp will do a six-month, three-well polymer pilot in the Polaris PA. “This pilot will determine polymer’s impact on injectivity, MI utility, oil rate, and reserves. Hilcorp North Slope will use this data to determine whether polymer expansion is economic in Orion and Polaris PAs.”
The company is conducting front-end engineering studies on L pad expansion and V pad gas separation to determine whether those projects are economic.
2021 POD review
Hilcorp told the division in its proposed 2022 POD, submitted Sept. 30, that its focus with the Western Satellites has been “on returning idle wells to service, optimizing production through the existing surface infrastructure, targeting reservoirs that had been under-developed, improving voidage replacement, maximizing MI utility, and improving operational efficiency.”
Those things combined, the company said, led to a 43% year-over-year increase in oil production from the Western Satellites for the 12 months from July 1, 2020, to June 30, 2021, compared to July 1, 2019, through June 30, 2020.
Hilcorp North Slope took over as operator at Prudhoe on July 1, 2020, after the sale of BP’s upstream assets was finalized effective June 30, 2020.
The company said the Western Satellite PAs produced some 9.417 million barrels of oil and 24.6 billion cubic feet of gas between July 1, 2020, and June 30, 2021, an increase of 2.837 million barrels of oil. The daily average for the 2020-21 period was 25,801 bpd of oil.
For the July 1, 2020, through June 30, 2021, period, Aurora averaged 5,968 bpd, Borealis 7,094 bpd, Midnight Sun 1,263 bpd, Orion 4,056 bpd and Polaris 7,420 bpd.
2021 POD activity
In July the Prudhoe working interest owners agreed to drilling in the Western Satellites and the division approved an amendment to Hilcorp’s 2021 POD for the Western Satellites.
The division said the Aurora, Borealis and Midnight Sun PAs produce primarily from the Kuparuk River formation while Orion and Polaris “produce oil with higher viscosity from the Schrader Bluff formation.”
In its 2022 POD, Hilcorp said it mobilized a drilling rig to the Orion PA in September 2021 and spud the L-206 well. The company told the division it plans to drill five wells from L pad and two from Z pad during the remainder of the 2021 POD period, and said one of the wells, the Z-221i is expected to spud in late December but will not be completed until 2022. Z-220, a Z pad producer, will likely move into the 2022 POD period “due to operational timing,” the company said.
A number of workovers were completed or are planned to be completed during the 2021 POD.
At the Borealis PA, Hilcorp recompleted two Z pad wells from the Ivishak to the Kuparuk formation: Z-31, recompleted and put on injection June 2, is currently on MI; Z-11A was recompleted and put on production June 18, with an initial stabilized production rate of some 350 barrels per day of oil.
In the Midnight Sun PA, a rig workover was proposed, but not executed. Hilcorp said an alternative procedure was found to achieve the work.
At Orion, Hilcorp said two rig workovers were scheduled to repair mechanically failed wells. L-203, following repairs, tested at some 1,000 bpd. At V-205, a rig workover on the 2021 list was moved to 2022 “due to long lead tangible order timing.”
Two rig workovers were done to add injection: V-137 was completed into the Schrader and put on injection; a rig workover at V-120 was “delayed into 2022 POD period due to workover scheduling.”
At the Polaris PA, three workovers were proposed to add injection, with work completed at S-216 and W-212, and a scheduled rig workover to convert S-15 to injection scheduled for the third quarter 2021.
Major facility projects in the 2021 POD period included completion of reinstating the Gathering Center 2 “slug catcher sand jetting system to improve solids and water handling capabilities.”
Hilcorp said it “continues to generate and evaluate opportunities to improve the western area gathering infrastructure.”
Western Satellite PAs
Hilcorp included background on the Western Satellite reservoirs, here supplemented with data from the Alaska Oil and Gas Conservation Commission, which provides profiles on oil and gas pools in the state, as well as monthly production by field and well.
Development of the Aurora reservoir began in July 2000, Hilcorp said, with production startup in November 2000 and water injection beginning in December 2001. Prudhoe Bay miscible gas for water-alternating-gas injection, WAG, was used for tertiary recovery at Aurora beginning in December 2003. AOGCC information on the Aurora oil pool describes it as within the Kuparuk River formation and defined by the 1969 Mobil Oil Corp. Mobil-Phillips North Kuparuk State No. 26-12-12 discovery well with the structure between 6,450 and 6,850 feet true vertical depth. AOGCC data shows Aurora production from S pad.
Hilcorp said development at the Borealis reservoir began in July 2021. Production startup was in November 2001, with water injection starting in June 2002. A pilot project using Prudhoe Bay miscible injectant, MI, for WAG for tertiary recovery began at Borealis in June 2007. AOGCC information on the Borealis oil pool says it is in the Kuparuk River formation and is produced from the L, V and Z pads. The hydrocarbon accumulation correlates with the interval between 6,534 and 6,952 feet measured depths in the West Kuparuk State 3-11-11 well.
Development of the Midnight Sun reservoir began in 1997, Hilcorp said, with production beginning in October 1998, water injection in October 2000 and MI in 2016. In AOGCC data on the Midnight Sun oil pool, the discovery well is listed as the 1997 Sambuca No. 1, later renamed PBU MDS E-100. The discovery was confirmed in 1998 by the Midnight Sun No. 1 delineation well, later renamed PBU MDS E-101. Midnight Sun is a Kuparuk River formation accumulation which correlates with the interval from 11,662 to 11,805 feet measured depth in the Sambuca No. 1. AOGCC production records show two wells in production at Midnight Sun in the 2021 calendar year through August, with production from E pad.
Hilcorp said development began at the Orion reservoir in December 2001, with production beginning in April 2002 and water injection in December 2003. Prudhoe Bay MI for WAG has been used since October 2006 for tertiary recovery. Orion is in the Schrader Bluff formation, and AOGCC information on the pool says Orion represents the PBU portion of the formation, which is also present in the Milne Point and Kuparuk River units. The accumulation at Orion was discovered in 1968 by the Kuparuk State No. 1 exploratory well and confirmed in 1998 by Northwest Eileen 2-01 and is defined as the hydrocarbons correlating with the interval from 4,549 to 5,106 feet measured depth in PBU V-201. AOGCC said the pool produces from the V and L pads with horizontal well drilling technology used extensively in the pool’s development.
The Polaris PA also produces from the Schrader Bluff formation. Hilcorp said development at the pool began in November 1997 with production beginning in November 1999 and water injection in May 2003. Prudhoe Bay MI was used in 2006 for WAG and then beginning again in 2009 for tertiary recovery. AOGCC said the Polaris oil pool is an accumulation correlating with the interval between 5,544 and 6,012 feet measured depths in the PBU S-200PB1 well, with production from the S and W pads.
