RESERVE POTENTIAL OF THE KAVIK GAS FIELD, NORTH SLOPE OF ALASKA

VERMA, M.K.¹, BIRD, K.J.², NELSON, P.H.¹, and BURRUSS, R.C.³, (1) U.S. Geological Survey, P.O. Box 25046, MS 939, Denver Federal Center, Denver, CO 80225, [email protected], (2) U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, (3) U.S. Geol Survey, National Center, MS 956, 12201 Sunrise Valley Drive, Reston, VA 20192

The Kavik gas field, located about 65 miles southeast of Prudhoe Bay in the Brooks Range foothills, was discovered in 1969 on a thrust-faulted anticline representing the western, down-plunge extension of the Sadlerochit Mountains. Despite being one of the larger and better defined foothills gas accumulations, the field has not been developed for lack of a North Slope gas transportation system. The U.S. Geological Survey has made the first public estimates of the size of this gas accumulation.

Three wells delineate the Kavik gas field, but only two penetrate the gas column, which is about 1,500 ft thick. Based on the gas pressure gradient from drillstem tests, the gas-water contact is estimated to be at 4,320 ft subsea (± 25 ft). At this depth, the field covers about 3,600 acres. The reservoir temperature and initial pressure are estimated at 122°F and 2,431 psi, respectively, at the datum of 3,500 ft subsea. The gas is dry (about 96% methane) and has a combined nitrogen and carbon dioxide content of 3%; the liquid-gas ratio ranges from 0.3 to 1.3 barrels per million cubic feet of gas.

Kavik reservoirs, in decreasing order of importance, include the Ledge Sandstone Member of the Ivishak Formation, the Sag River Sandstone, and the Shublik Formation, all of Triassic age. Considering uncertainties related to reservoir continuity and porosity and the elevation of the gas/water contact, the gas-in-place volume is estimated to range from 135 to 247 billion standard cubic feet (BSCF). Assuming a 70% recovery factor, the Kavik field is estimated to have 95 to 173 BSCF of technically recoverable gas.