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AOGCC approves Nanuq-Kuparuk injection ConocoPhillips will use enhanced recovery injection for Alpine satellite field; three horizontal wells planned for oil pool By Kristen Nelson Petroleum News
The Alaska Oil and Gas Conservation Commission has approved a plan by ConocoPhillips Alaska for water alternating miscible gas injection at the Nanuq-Kuparuk development, concluding that injection of water and miscible gas will significantly improve recovery. Nanuq is an Alpine field satellite in the Colville River unit, the westernmost development on the North Slope.
Three horizontal wells are planned for the Nanuq-Kuparuk oil pool, two producers and one injector. Water injection is scheduled to begin in late 2006 followed by miscible gas injection beginning in 2007. Production from the Nanuq-Kuparuk oil pool and the shallower Nanuq oil pool will be commingled on the surface at the Colville River unit CD-4 drill site and further commingled with production from the Alpine pool and other Alpine satellite pools before separation at the Alpine Central Facility on the CD-1 drill site.
Peak production rates from the Nanuq-Kuparuk are expected to be between 3,700 and 8,500 barrels per day, with waterflood injection rates expected to peak at 3,500 to 7,900 bpd. Miscible gas injection rates are estimated to peak at 3.5-8 million standard cubic feet of gas per day. Recovery of 57-77% expected Original oil in place in the Nanuq-Kuparuk pool is estimated at 21 million to 36 million barrels. With primary recovery an estimated 15 percent, or 3 million to 5 million barrels, would be recovered. Primary plus waterflood would recover 40 to 52 percent, or 8 million to 19 million barrels. The proposed plan, primary plus waterflood plus water alternating miscible gas, is expected to recover 57 to 77 percent or 12 million to 28 million barrels.
The Nanuq-Kuparuk reservoir is a shallow marine sandstone approximately 10 feet thick some 900 feet true vertical depth beneath the overlying Nanuq oil pool. The Nanuq-Kuparuk is similar to the Kuparuk C sands developed in the Kuparuk River and Milne Point units.
ConocoPhillips told the commission at an October hearing that it expects to begin production from both Alpine satellites, Nanuq, which lies south of Alpine, and Fiord to the north, in November 2006. The company said there are some 84 million to 169 million barrels of oil in place at Nanuq in addition to the 21 million to 36 million barrels in the deeper Nanuq-Kuparuk formation.
Total recovery in the shallower Nanuq oil pool is estimated at 26-41 percent, with enhanced recovery, water alternating miscible gas. Combined recovery from the two pools at Nanuq is estimated at 33 million to 98 million barrels, the company told the commission in October. The combined peak production rate for CD-4 is estimated at 10,000 to 15,000 barrels per day.
ConocoPhillips has a 78 percent working interest in the Colville River unit and is the operator; Anadarko Petroleum holds the remaining 22 percent interest. Arctic Slope Regional Corp. and the State of Alaska are both royalty owners. Initial injection seawater Fluids requested for injection include: source water from the Beaufort Sea; miscible gas from the Alpine Central Facility; produced water from the Nanuq-Kuparuk oil pool; produced water from the Alpine oil pool and other Alpine satellites; and small amounts of fluids collected from sumps, hydrotests, rinsate water from washing mud hauling trucks, excess well-work fluids and treated camp waste water. Seawater will be the initial waterflood source water.
The commission authorized fluid injection for pressure maintenance and enhanced recovery within the Nanuq-Kuparuk development area into strata correlating with the interval of 7,956 feet to 7,972 feet measured depth in the Nanuk No. 2 well.
The commission said seawater waterflood source water will be compatible with the Nanuq-Kuparuk reservoir, but noted that compatibility has not been demonstrated for produced waters, mixtures of waters, non-hazardous liquids collected from sumps, hydrotests, well work, rinsate from washing mud-hauling trucks and treated camp waste water.
The commission authorized injection using source water from a seawater treatment plant; miscible gas from the Alpine Central Facility; tracer survey liquid to monitor reservoir performance and small amounts of other non-hazardous liquids.
But the commission said that prior to injection of any liquid other than seawater or any mixture of liquids, compatibility with the Nanuq-Kuparuk reservoir must be demonstrated. It further said that injection of fluids other than those listed without prior authorization is considered improper Class II injection.
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