Prudhoe Bay field - PetroWiki

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The Prudhoe Bay field, located on the North Slope of Alaska, is the largest oil and gas field in North America.[1][2][3][4][5] The main Permo-Triassic reservoir is a thick deltaic high-quality sandstone deposit about 500 ft thick with porosities of 15 to 30% BV and permeabilities ranging from 50 to 3,000 md. The field contains 20 109 bbl of oil overlain by a 35 Tcf gas cap. Under much of the oil column area, there is a 20- to 60-ft-thick tar mat located above the oil-water contact (OWC).