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Miscible gas EOR for Kuparuk pool at Milne Point will increase oil recovery by 30-40 million barrels
Kristen Nelson
The Alaska Oil and Gas Conservation Commission has approved amendments requested by BP Exploration (Alaska) Inc. to area injection order No. 10 for the Milne Point unit. Injection order No. 10-A, approved Oct. 29, amends the 1986 order to cover a proposed miscible gas enhanced recovery project in the Kuparuk River oil pool within the Milne Point unit.
BP has conducted an immiscible water-alternating gas enhanced oil recovery project in the Kuparuk River pool at Milne Point for several years. A water flood project has been and continues to be conducted in the Milne Point Schrader Bluff oil pool.
BP is producing the Kuparuk River formation at Milne Point from eight pads. Water and lean (immiscible) gas are being injected at four of the pads, only water at the other four. Immiscible water-alternating gas wells within the project area will be switched to miscible water-alternating gas.
The commission said that the predicted daily rate of hydrocarbon gas injection is approximately 25 million standard cubic feet. The miscible injectant will be manufactured by blending 4,000-5,000 barrels per day of imported natural gas liquids from the Prudhoe Bay unit with approximately 20 million standard cubic feet of produced gas from Milne Point production.
Facilities needed to implement the project include a new 8-inch pipeline from an existing pipeline tied into the Oliktok pipeline which carries natural gas liquids from the Prudhoe Bay unit to the Kuparuk River unit, a custody transfer meter to measure the NGLs imported for use at Milne Point and pumps in the Milne Point central facilities pad to increase pressure of the NGLs.
Increased recovery expected BP predicts the MWAG project will increase ultimate oil recovery by 7.5-10 percent of original oil in place compared to water flood, resulting in added reserves of 30-40 million barrels (excluding NGLs). The immiscible water-alternating gas project was projected at 1-3 percent incremental over water flood.
Production increase is expected to peak at 9,000 barrels of oil per day.
BP told the commission that the MWAG project utilizes a vaporizing-condensing process similar to EOR projects in the Kuparuk River unit, Prudhoe Bay unit, Endicott and Point McIntyre.
Because of the complex faulted nature of the Kuparuk River formation at Milne Point, the formation was not developed on a regular pattern basis. The commission said that BP has characterized the reservoir using fault blocks or hydraulic units. There are 77 separate hydraulic units, of which 46 are currently targeted for MWAG. Each hydraulic unit is from one to five patterns — areas bounded by layouts of injectors and producers.
The commission said that BP plans significant surveillance activities both field-wide and within hydraulic units, with focus given to maximize areal and vertical sweep of the reservoir.
BP plans to maintain reservoir pressure close to the original pressure of approximately 3,500 pounds per square inch.
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