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Northstar Kuparuk gas injection request
Hilcorp officials explain to AOGCC why the company wants to start injection into the A & C sands through converted production well
Alan Bailey Petroleum News
Hilcorp Alaska anticipates a 4 million to 5.5 million barrel boost in oil recovery from Kuparuk sands in the Northstar oilfield, if the company implements gas injection into the field’s Kuparuk oil pool, company officials said during an Alaska Oil and Gas Conservation Commission hearing on Sept. 6. As previously reported in Petroleum News, Hilcorp has applied to the commission for permission for the gas injection. Without gas injection, ultimate oil recovery from the pool would be limited to some 9 million barrels, the company has said.
The field is operated from a gravel island offshore in the Beaufort Sea, with the unit straddling state nearshore waters and waters of the federal outer continental shelf.
Jim Shine, Hilcorp land manager, told the commission that the field has three participating areas: the Northstar, Fido and Hooligan participating areas. The Northstar and Fido participating areas have reservoirs in the Ivishak formation, equivalent to the main reservoir of the Prudhoe Bay field. The Hooligan has reservoirs in the shallower Kuparuk A and C sands.
Production history Production from the Ivishak began in 2001. Sustained production from the Kuparuk C began in 2010 from a single well, the NS-08 well. Production from both the Kuparuk A and C began in 2016 through another well, the NS-18 well. And the NS-15 well came on line from the A and C sands in 2017, Hilcorp reservoir engineer Chris Kanyer told the commission.
Gas from the Kuparuk, produced along with oil and condensate, has been injected into the Ivishak reservoir, for enhanced oil recovery from that reservoir. But increased gas production, especially from the N-15 well, has enabled the reservoir pressure in the Ivishak to be restored to somewhere close to its original level. So now, with more than enough gas being produced to support Ivishak production, there is adequate gas for injection into the Kuparuk - Hilcorp wants to convert the NS-18 into a gas injection well for this purpose.
Hilcorp geoscientist Daniel Yancey told the commission that the Kuparuk sands lie between confining shale layers above and below: 2,000 feet of HRZ and Colville shales above, and more than 1,500 feet of the Kingak below. Hilcorp well integrity engineer Wyatt Rivard presented evidence, demonstrating that anticipated downhole pressures resulting from the planned gas injection would be well below the fracture pressure for the shales.
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