The Alaska Oil and Gas Conservation Commission has approved pool rules and an enhanced recovery injection order for the Minke oil pool at ConocoPhillips Alaska's Colville River unit.
The Minke oil pool is part of the Brookian Nanushuk formation, the commission said, correlating with the portion of the Nanushuk in the Colville River unit CD-22 well between 5,222 and 6,433 feet measured depth or 4,333 to 5,194 feet true vertical depth.
The Minke oil pool "is part of the same, thick Nanushuk progradational sequence, but is not in communication with" the Nanushuk in the Pikka unit, the Qannik oil pool in the Colville River unit, the Coyote oil pool in the Kuparuk River unit and the proposed Willow development in the Bear Tooth unit, the commission said in its Feb. 26 approvals.
In describing the pool's stratigraphy, AOGCC said that Minke "is thinly bedded throughout and comprised of very fine-grained sandstones, siltstones, and mudstones. The pool thins to the west and thickens to the east. There is a presumed oil water contact at 4,400 feet TVDSS which, combined with the degrading reservoir quality with depth, limits the proposed development to approximately the upper 100 feet of the proposed pool."
The proposed Minke oil pool was penetrated by numerous Colville River unit CD5 drillsite and exploratory ice pad wells, the commission said. "Initially this interval was not considered to be a significant hydrocarbon bearing zone."
ConocoPhillips's CD5-32X well, drilled in January 2024, a dedicated exploration well "demonstrated the existence of this resource."
The proposed Minke oil pool is within the Colville River unit but extends beyond the Minke participating area established by the Alaska Department of Natural Resources' Division of Oil and Gas, the commission said.
Development plan
ConocoPhillips plans a three-well pilot project with two injectors and one producer to determine optimal design for full field development of the Minke oil pool, the commission said.
Subject to results from the pilot project, the full development plan calls for an estimated nine "horizontal multi-stage fracture-stimulated producers" and eight injectors, also "horizontal multi-stage fracture-stimulated injectors."
Water-alternating gas injection is a possibility.
Pilot project wells will have inter-well spacing of 1,250 feet "to evaluate pressure communication between injectors and producers at that distance."
"Upon completion of this pilot project and other evaluations, CPAI will expand development to the full pool adjusting the current plan as required based on the pilot project results," the commission said.
The wells will trend southeast to northwest with horizonal sections from 4,000 to 10,000 feet in length.
Production from Minke will be commingled at the surface with other Colville River unit and Greater Mooses Tooth unit production -- and production from future pools -- and processed through the Alpine Central Facility.
Injection plans
In its September application for injection, ConocoPhillips said the fluid quality of the oil pool requires secondary recovery for economic production, with water injection, the main recovery process at Colville River, planned for Minke.
Primary recovery is estimated at 5-10% of original oil in place, with an additional 15-25% from waterflood, for a total of 20-30%. Gas injection is being evaluated.
The original oil in place estimate for Minke is from 80 million to 150 million stock tank barrels for the area planned for development from CD5.
"The largest remaining uncertainty for the Minke development is the question of interconnectivity of the reservoir at the proposed development scale" which is 1,000 to 1,500 foot well spacing, the company said.
In its approval order the commission noted stock tank oil of 34.8 degree API gravity.
A water sample from the exploration well shows formation water at Minke has salinity over 10,000 parts per million, so an aquifer exemption is not necessary for the project, the commission said.
Initial injection will be produced water from the Alpine Central Facility, including Colville River and Greater Mooses Tooth produced water and seawater from the Kuparuk River unit seawater treatment plant. The commission said additional fluids may be injected, with water injection rates of 2,000 to 8,000 barrels per day expected.
"Gas injection rates are not yet determined as additional work is being done to evaluate the potential of using gas injection to enhance oil recovery," the commission said.
