There has been intermittent production from the Ugnu formation at the Milne Point field, starting with a pilot run by BP Exploration (Alaska) in 2003 when it was the field owner and operator. There was Ugnu production in 2003, 2004, 2008, 2011, 2012 and 2013.
After Hilcorp Alaska took over as Milne Point operator, with a 50% working interest ownership, in 2014, there was another hiatus in Ugnu production, but it began again in 2019 and has continued.
Ugnu is the shallowest of the North Slope accumulations, heavy oil which is difficult to produce.
In late November, Hilcorp applied to the Alaska Oil and Gas Conservation Commission for a pilot enhanced oil recovery project in the Ugnu formation at Milne Point. The commission has public noticed the application, received Nov. 29, and tentatively scheduled a public hearing for Jan. 11, if a written request for a hearing is received by 4:30 p.m., Dec. 22. The commission said that if it does not receive a timely request for a hearing, it may consider issuance of an order without a hearing and said it would update its events webpage with any changes on or after Dec. 22.
Commission regulations require operators to apply for and be granted an order authorizing EOR injection before injection can begin.
Hilcorp application
In its application Hilcorp said it is proposing polymer injection at the Milne Point S pad and said polymer is not currently approved for EOR for this area and prior temporary administrative approval for water and gas injection into the Ugnu sand has expired.
This project builds on work begun by BP in 2003, Hilcorp said, and is designed to “gather the data necessary to determine the appropriate spacing for paired Ugnu producer and injection wells at S-pad. If the pilot proves successful, potential exists to justify a project throughout the field, including the establishment of formal pool and area injection rules for the MPU Ugnu sand.”
Two horizontal injectors would be used to support an existing horizontal Ugnu producer, S-203, which was drilled and brought online in 2019. S-203 is producing, but “requires pressure support from injection wells.”
“Hilcorp plans to test the economic viability of waterflooding and polymer flooding in the Ugnu sand,” the company said.
Hilcorp said the pilot, including waterflooding and polymer flooding, will involve a pattern with single producer and two injectors and potentially up to five patterns, which would involve five producers and five injectors, all at S pad.
Total recovery of some 9.25% of Ugnu original oil in place is expected, Hilcorp said, compared with 4-8% OOIP recovery with primary depletion.
Wells planned
The S-22 well is an existing horizontal well, Hilcorp said, drilled to test the Ugnu. It will be converted to an injector during the pilot program.
Hilcorp also plans to drill a new injector, S-204, which will offset the S-203 producer opposite the S-22.
For injection fluid, Hilcorp said it would use produced water from the Kuparuk River, Schrader Bluff, Sag River and Ugnu sands which is separated from oil and gas at the Milne Point Central Processing Plant.
Some 2,000 barrels of water per day will be needed for the two Ugnu sand injectors, Hilcorp said, and that volume “may be increased as needed to make up reservoir voidage or as additional injectors are added.”
Other fluids which may be used for injection include a polymer solution that the company is currently using for L pad Schrader Bluff formation polymer flooding and solution gas re-injected to maintain reservoir pressure, along with tracer survey fluid to monitor reservoir performance.
The pilot project will inject into the MA, MB, MD and MF intervals of the Ugnu formation, Hilcorp said, also known as the M-interval of the Lower Ugnu.
Ugnu production
Through October of this year, total Ugnu production from Milne Point is 290,826 barrels since BP began production in 2003.
Hilcorp said S-203 is currently producing 13.5 API oil.
The interval planned for injection is between measured depths of 3,890 feet and 4,550 feet.
Hilcorp said the M-interval extends from 3,890 feet measured depth to 4,150 feet MD in the MPG-01 well.
