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This month in history: ConocoPhillips asks to expand Alpine pool
20 years ago this month: Company estimates area north and west of Slope field contains some 31-55 million barrels of oil in place Kristen Nelson Petroleum News
Editor's note: This story first appeared in the Aug. 8, 2004, issue of Petroleum News.
ConocoPhillips Alaska believes the Alpine oil field may extend farther to the north and west than originally believed and has applied to the Alaska Oil and Gas Conservation Commission to expand the area of the Alpine oil pool covered by the commission's production and injection orders.
The proposed expansion area is within the Colville River unit, and drilling would be from Colville River unit drill site CD2.
ConocoPhillips said information for the requested expansion comes from results of its development drilling, which "has greatly increased our knowledge of the distribution of the sands" in the Alpine participating area and has allowed it to better correlate seismic data with reservoir sands. Original oil in place in the expansion area is estimated at 31 million to 55 million barrels, and the company said that range "will undoubtedly change as new drilling information becomes available."
ARCO Alaska Inc., ConocoPhillips Alaska's predecessor, told the commission in 1999 that Alpine contained an estimated 960 million barrels of oil in place, and that with horizontal wells and a miscible water-alternating-gas oil recovery process implemented at startup, recovery was expected to be 45 percent, or some 429 million barrels.
At a midpoint in the 31 million to 55 million barrel range the proposed expansion area would add less than 5% to oil in place at the field.
Five additional wells planned Five wells are planned in the expansion area, all on tracts leased from the state and the Arctic Slope Regional Corp., and the company told the commission it has applied to drill the wells as tract operations. Once production has been established from the expansion area, the company said, it would apply to the Alaska Department of Natural Resources and Arctic Slope Regional Corp. to expand the Alpine participating area, the acreage within the unit from which production occurs.
Existing Alpine facilities will be employed to process the oil produced, the company said.
ConocoPhillips told the commission that it has tested vertical net pay thickness in the northern row of wells, and estimates it has 19 to 40 feet of reservoir quality Alpine sand "at the toe of the current northern row of development wells at CD2."
The company said it expects to continue its pattern of horizontal wells into the extension area. It is possible "that lower quality reservoir rock will be encountered in the proposed expansion area," in which case propped hydraulic fracture stimulation may be evaluated.
CD2 was designed to accommodate 60 wells, ConocoPhillips said, and no new gravel is expected to be needed for the expansion.
Alpine, which came online in November 2000 at some 80,000 barrels per day, has recently been producing at 100,000 to 105,000 bpd, and facilities expansion work this year and next will increase produced water handling capacity and allow production of 140,000 bpd.
The Colville River unit itself was expanded to the northwest earlier this year, and a new prospect, Iapetus, will be drilled in that area by June 2005, according to the terms of the unit expansion, with a second well by June 2006.
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