Hilcorp files amended Northstar ops plan
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Kay Cashman Petroleum News
On Jan. 6 Hilcorp Alaska LLC filed an amended 17th plan of development for the Northstar unit with Alaska’s Division of Oil and Gas. The POD, which also includes an updated progress report for work done under the 16th POD, covers Feb. 13, 2021, through Feb. 12, 2022.
The Northstar oil field is operated from a five-acre man-made gravel island offshore the central North Slope in the Beaufort Sea. The unit, which is six miles off the Beaufort Sea coast and a little over 11 miles northwest of Prudhoe Bay, straddles state nearshore waters and waters of the federal outer continental shelf.
The Alaska Department of Natural Resources’ Division of Oil and Gas and the U.S. Department of Interior’s Bureau of Safety and Environmental Enforcement jointly manage the four state and two federal leases in the Northstar unit, which is comprised of three oil sand accumulations - the Ivishak sands in the Northstar participating area, the Ivishak sands in the Fido PA and the Kuparuk sands in the Hooligan PA.
Northstar production began in November 2001 under the operatorship of primary leaseholder BP, who in 2014 brought privately held Hilcorp’s Alaska subsidiary in as a significant working interest owner and operator. Then in August 2019 the two companies signed an agreement for BP to sell the rest of the unit’s working interest to Hilcorp.
Updated annual report In its 16th POD, which covers the period from Feb. 13, 2020, through Feb. 12, 2021, Hilcorp said it anticipated Northstar production would be maintained. Northstar output averaged 9,221 barrels per day of oil from Jan. 1 through Sept. 30, a volume including both black oil and natural gas liquids. The previous POD reported an average of 10,095 bpd (also black oil and NGLs combined) for Jan. 1, 2019, through Aug. 31, 2019.
Northstar field averaged 6,912 bpd in November, down 1,952 bpd, 22%, from an October average of 8,864 bpd and down 28.2% from a November 2019 average of 9,629 bpd. Crude oil represented 83.3% of the field’s production in November, 5,758 bpd, up 7.6% from October and down 18.3% from November 2019. Northstar NGL production for November averaged 1,154 bpd, 16.7% of the field’s production, down 67.1% from October and down 55.3% from November 2019.
During the 16th POD period Hilcorp had not expected to do any grassroots or sidetrack drilling. Rather, the company intended to implement a workover program and perform some surface facility operations that would bolster production, the bulk of which is black oil.
Surface facility work was to include building an ice road for the Northstar Propane Chiller Project module deliveries, and then install support frames, set chiller modules and install associated chiller system piping. The chiller was to be commissioned during the summer for improved NGL recovery when ambient temperatures were warmer.
What Hilcorp and its contractors have accomplished so far is the NS-25 well casing repair, the ice road and all the planned surface chiller work.
They also did the following to increase flow rates from three Northstar wells:
* Installed a subsurface safety valve in the NS-25 well.
* Added perforations to the NS-05 well, though results from this effort were minimal.
* Added perforations to the NS-11 well, which also yielded negligible results.
Hilcorp said it did not acidize any Kuparuk PA producer wells due to “undervoiding” in the Kuparuk oil pool: “With a current voidage replacement ratio of less than one, acidizing a Kuparuk producer well would exacerbate the undervoidage. Therefore, the decision was made to defer any acidizing projects until there is a more favorable voidage replacement ratio.”
17th plan of development The same long-range development work included in the 16th POD is in 17th plan activities, such as the intention to delineate and bring into production all underlying oil or gas reservoirs, exploring the possibility of importing gas for reinjection from the Prudhoe Bay unit via the existing Northstar Island gas pipeline that runs from the Central Gathering Facility to Northstar, and to confirm the existence of the Kuparuk oil rim.
Hilcorp does not plan any exploration or delineation activities in the unit that are outside the existing three PAs, nor does it anticipate any sidetrack or grassroots drilling during the 17th POD period.
Hilcorp does, however, intend to convert existing Kuparuk oil pool producer NS-15 well to an injector to increase gas injection; plus, it will interrupt output for eight to 10 days this summer for maintenance activities.
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