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Division approves Alkaid unit; Great Bear plans drilling in 2021
Kristen Nelson Petroleum News
The Alaska Department of Natural Resources’ Division of Oil and Gas has approved an application from Great Bear Petroleum Ventures for formation of the Alkaid unit.
The company applied for unit formation in August (see story in Sept. 13 issue of Petroleum News). The approval is dated Nov. 2.
There are four state oil and gas leases in Alkaid, a total of 22,804 acres, along the trans-Alaska oil pipeline on the central North Slope some 13 miles south of the Prudhoe Bay unit.
The division said Alkaid has been part of scattered exploration efforts since the 1960s, and remains lightly explored, with no wells drilled in the unit area prior to 2012 when Great Bear began a drilling program to evaluate unconventional resources in the area and drilled the Alcor 1 and Merak 1 wells.
“Following a significant decline in oil price, Great Bear’s interest shifted to the conventional targets located in the AKU area,” where the company spud the Alkaid 1 well in 2015, the division said.
Alcor 1, Merak 1 Alcor 1, the first well drilled in the unit area, was spud in June of 2012 and reached a final depth of 10,812 feet measured depth, 10,802 feet true vertical depth. The division said it penetrated numerous formations that produce conventionally on the North Slope, including the Kuparuk and Ivishak formations, as well as unconventional targets - the Hue Shale/HRZ, Kingak and Shublik.
Great Bear spud the Merak 1 in August 2012, immediately after Alcor 1 was drilled. Merak reached a MD of 11,094 feet and a TVD of 11,081, penetrating the same formations as the Alcor well.
Both wells were plugged and abandoned.
Alkaid 1 Great Bear didn’t drill again in the area until February 2015, when it spud Alkaid 1. It planned to drill that well to the Kuparuk, but it was only drilled to 8,595 MD, 8,485 TVD, the division said, with operational issues tied to Sag River flooding preventing flow testing at the time; the well was suspended.
Great Bear re-entered the Alkaid and successfully flow tested it in February 2019. The division said a 6-foot interval at 8,158-8,164 feet was perforated in Upper Brookian sands, “and a one-stage hydraulic fracture treatment was initiated to stimulate the well.”
The well was flowed for some 24 hours and produced 108 barrels of 38 degree API oil and 300 barrels of water, with the well gas lifted during the test. Two shallower zones were tested in addition to the deeper perforations, with water recovered from the West Sak at 5,378-5,398 feet MD and the Ugnu also “interpreted to be wet.”
Following the flow test, the Alkaid was again suspended.
Potential hydrocarbon accumulation “Based on non-confidential well control, there is a potential hydrocarbon accumulation within the proposed Alkaid Unit,” the division said.
The target at Alkaid is called “the Brookian Zone of interest” by Great Bear. “It is composed of relatively thin bedded sands with interbedded shales and silts,” the division said, and is quite thick in the Alkaid unit area, with some 400 feet of the Brookian intersected in the Alkaid well, which did not reach an oil-water contact or the bottom of the formation.
The division said Great Bear provided comprehensive interpretation and analysis of available data in support of its unit application, including interpretations of 3D seismic, maps based on seismic attribute analysis, structure maps, interval isopachs and net pay maps integrating seismic and well data and geologic cross sections.
Great Bear has interpreted 3D seismic and analysis of its recently drilled wells, and “has identified the Brookian section in the AKU area as their preferred target to progress towards a commercial development,” and, the division said, review of confidential data and interpretations of that data “reasonably supports an interpretation that the unit encompasses the minimum area required to include all or part of a reservoir and all or part of a potential hydrocarbon accumulation,” with the area “proven through drilling and testing.”
The division said, “additional delineation work will determine the commercial viability of the Brookian oil-bearing strata at and away from the Alkaid 1 well.”
While the potential hydrocarbon accumulation area meets the regulatory requirement for inclusion in a unit, it “will require drilling, testing, and additional delineation work in order to determine its commercial viability,” the division said.
Plan of exploration approved The division has approved the plan of exploration which accompanied Great Bear’s unit application, effective Nov. 2 and running through Nov. 1, 2022.
The company listed a number of non-drilling activities: reprocessing some 50 square miles of merged 2012-16 3D datasets, which will be completed prior to drilling the Alkaid 2 to inform the target interval for the lateral. Great Bear said the work was unlikely to result in relocation of the drill site or tophole location for the well, “but it could result in slight deviation from a true vertical well before hitting TVD.”
Among other non-drilling activities, Great Bear said it would: “Engage an outside engineering firm to produce an engineering study on a conceptual ‘hot tap’ of TAPS within or near the Alkaid and Talitha Units, working in consultation with Alyeska Pipeline Service Company.”
(Great Bear applied for a unit at Talitha at the same time it applied for the Alkaid unit; the division has not yet issued a decision on that application.)
Planned drilling activities include the Alkaid 2, with a planned TVD of 8,000 feet “to the basin floor of the Brookian, a level not reached” at Alkaid 1, Great Bear said.
“Multiple interesting zones may be encountered throughout the drilling. The well will penetrate the entirety of the Brookian section. This will include an evaluation of the deltaic interval of the Brookian progradation,” the company said.
The lateral for Alkaid 2, estimated at 10,000 feet, will run toward the southwest and will be fracture stimulated.
There will be a long-term production test “to determine the decline curve and production profile” at Alkaid 2, with the test long enough to establish the initial production rate, slope of the decline curve and the rate at which the decline curve levels off so that the production tail can be accurately predicted.
“We currently estimate that the production test will be six to nine months in duration,” Great Bear said.
Alkaid 2 drilling operations are scheduled for the summer of 2021 from a gravel pad just west of the Dalton Highway, with the pilot production test projected from September 2021 through mid-2022.
Great Bear said a number of factors would determine whether Alkaid 2 results support drilling of Alkaid 3.
If that well is drilled it would be in the winter of 2022, with the pilot production test running from June 2022 through late 2022.
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