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AOGCC approves 3-year Narwhal water pilot
Enhanced recovery injection will provide for pressure maintenance, enhanced recovery, from Colville River unit Narwhal reservoir
Kristen Nelson Petroleum News
The Alaska Oil and Gas Conservation Commission has approved an application from ConocoPhillips Alaska for a pilot enhanced recovery injection project in the Narwhal reservoir at the Colville River unit.
In a Dec. 17 enhanced recovery injection order the commission said ConocoPhillips drilled the CRU CD4-595 well in June 2019 to determine feasibility of drilling and completing development wells at the Narwhal reservoir from the CD4 drill site.
At a ConocoPhillips analyst and investor meeting Nov. 19 in Houston, Michael Hatfield, president, Alaska, Canada and Europe, said the long-term flow test on the 2019 Narwhal horizontal well drilled from drill site CD4 “exceeded expectations” with a peak test rate of 4,500 barrels per day. “We encountered a consistent, thick oil-bearing sand along the full length of the horizontal lateral. The well test established high productivity.”
Hatfield said production at Narwhal is slated to start in 2022 through Alpine facilities. Another winter exploration season is needed to finalize appraisal at Narwhal, he said.
Scott Jepsen, ConocoPhillips Alaska senior vice president, told the Resource Development Council’s annual conference Nov. 20 that Narwhal will be on production as early as 2022 from CD4 “and a new pad called CD8 could come on production in 2025.”
CD4-595 ConocoPhillips Alaska told the commission in its September application for a water injection pilot that CD4-595 was drilled in June “to understand the ability to drill, complete, and produce the Narwhal horizon.” The company said the first injector would be drilled in October, with injection planned to begin in January and a second injector possible based on results from the first.
Narwhal is expected to be developed as a line drive water alternating gas flood with horizontal producers and injectors. “The pilot results will inform whether this development concept is optimal,” the company told the commission.
In its order the commission said: “The proposed pilot injection project would evaluate the feasibility of implementing an enhanced recovery project in the Narwhal Reservoir.” Four wells in the Colville River unit have penetrated the Narwhal Reservoir, the commission said, along with more than 10 wells in the vicinity of the Colville River and Pikka units.
No pool defined The commission said since the Narwhal Reservoir is still in the appraisal stages, a formal pool has not been defined.
“The Narwhal Reservoir sands are broadly age equivalent to the Nanushuk Group,” AOGCC said, noting that ConocoPhillips proposes a definition of the reservoir as the accumulation of oil common to and correlating with the accumulation found in the Qugruk 3 well from 4,192 to 5,152 feet measured depth. The commission said a full characterization of the hydrocarbon properties in the Narwhal Reservoir is not currently available, but exploratory well data “suggests the oil is slightly undersaturated.”
Since the Narwhal Reservoir is still being appraised there is no in place or recoverable reserves information available. “Modeling indicates recoveries of less than 5% without injection support and approximately 30% under waterflood,” the commission said.
The commission said an enhanced recovery injection order is appropriate to authorize the proposed pilot injection project since reservoir simulation modeling shows water injection should “substantially improve oil recovery, but the technical and economic feasibility of conducting such an operation is not currently known.”
The commission authorized the pilot and said the order would expire three years after the month in which injection began unless it granted an extension.
Injection fluids The commission said the anticipated water injection rate for the pilot project is 2,000 to 8,000 barrels of water per day per injection well.
Fluids authorized for injection are: source water from the Kuparuk River unit seawater treatment plant; produced water from the Colville River and Greater Moose’s Tooth units; fluids used during hydraulic stimulation of the injection well; tracer survey fluids to monitor reservoir performance; fluids used to improve near wellbore injectivity; fluids used to seal wellbore intervals which negatively impact recovery; fluids associated with freeze protection; standard oilfield chemicals; and sump fluid, hydrotest fluid, rinsate generated from washing mud hauling trucks, excess well work fluids and treated camp effluent and mixtures involving such fluids.
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