Mustang Holding LLC, operator of the Southern Miluveach unit, has applied to the Alaska Oil and Gas Conservation Commission for an area injection order to allow enhanced oil recovery injection in the portion of the Kuparuk River oil pool within the Southern Miluveach unit. Mustang Holding is a Finnex Operating company. Finnex acquired Mustang from the Alaska Development and Export Authority last fall and has been working to bring the field back into production; it was in production for just a month in 2019 under developer Brooks Range Petroleum.
In the June 3 application to AOGCC Mustang said first injection into the SMU portion of the Kuparuk oil pool is expected in the fourth quarter of this year, with fluids injected for pressure maintenance and enhanced recovery of hydrocarbons.
The Kuparuk oil pool in the SMU is a continuation of Kuparuk C and Kuparuk A sands "adjacent to the southwest portion of the Kuparuk River Unit," Mustang said.
Phase 1 includes re-installation of the production facilities, re-entering existing wells, reconnecting the Mustang Pipeline and returning the field to production from as many as four production and injection wells by year-end.
Additional wells will be drilled in phase 2 to keep production in the target range of 4,000 barrels per day, and will include expansion of waterflood operations, Mustang told the commission.
Depending on results from earlier phases, additional wells will be drilled to bring the total to as many as 11 horizontal or vertical producers and 10 horizontal or vertical injectors. Mustang said the early production facility would be "debottlenecked or replaced by additional facilities modules s warranted by longer term production results, reservoir performance, and potential third party or multi-horizon Mustang field development."
AOGCC has tentatively scheduled a hearing on the application for Aug. 27 at 10 a.m. but said if it does not receive a timely request for a hearing it may issue an order without a hearing.
Development plans
Length of the horizontal sections of the development wells will be up to 6,000 feet within the reservoir, with some wells producing from both the Kuparuk C and Kuparuk A reservoirs, and hydraulic fracture stimulation may be needed to "enhance productivity and improve vertical injection sweep," Mustang said.
Waterflooding may be followed by either lean gas or miscible gas injection, with production and injection managed to maintain reservoir pressure. Either produced water or seawater will be used for injection, with seawater from the ConocoPhillips Alaska-operated seawater pipeline.
Gas for injection will be from SMU processing facilities and Mustang said future availability of gas for injection is not known, but some form of IWAG (immiscible water alternating gas) flood, MWAG (miscible water alternating gas) or rich gas injection may be used in one or more injection patterns to enhance production, with economic evaluation of IWAG and MWAG determining feasibility of their use at SMU.
Injection pool
Mustang said the SMU Kuparuk pool is the accumulation common to and correlating with 6,006 feet vertical depth and 6,090 feet vertical depth in the North Tarn 1A, with the primary Kuparuk reservoirs in the proposed injection order Kuparuk C and Kuparuk A.
Combined thickness ranges from 0 to 80 feet, with the primary reservoir, Kuparuk C, ranging from 0 to 35 feet and Kuparuk A ranging from 0 to 80 feet.
Liquids proposed for injection include source water from the seawater treatment plant; produced water from the SMU Kuparuk River field; enriched hydrocarbon gas; lean gas; fluids used during hydraulic stimulation; tracer survey fluids; fluids used to improve near wellbore injectivity; fluids used to seal wellbore intervals; fluids associated with freeze protection; and standard oilfield chemicals.
Mustang said maximum injection rate for each injector well is some 6,000 barrels of water per day and 6 million standard cubic feet of gas per day, with rates "confined by injection pressures as to not exceed the overburden pressure gradient and cause fractures to penetrate through the confinement layer."
Recovery
"The primary uncertainties in the development of the SMU Kuparuk Oil Pool are the lateral continuity of the relatively thin sandstones and the effective displaceable pore volumes," Mustang said, with seismic indicating "laterally continuous productive sandstones over the development area with some compartmentalization possible."
Hydraulic fracturing "will aid in connecting the more poorly developed sandstone intervals."
Mustang said primary recovery is expected to be 10-15% of the original oil in place, with waterflood adding 10-25% to that for a total of up to 35%.
Gas injection could add to recovery, the company said, with historic incremental recovery from the addition of gas injection from 1-5% with IWAG and 3-15% with MWAG.
--KRISTEN NELSON
