The Kuparuk River oil field is located on the Alaskan Arctic North Slope in the Colville-Prudhoe trough some 25 mi (40 km) west of the Prudhoe Bay field. The 23° API crude is similar in type to that in the Prudhoe Bay field. The Kuparuk reservoir, however, is in Early Cretaceous clastics of the Kuparuk River Formation, stratigraphically higher than at Prudhoe. The origin of the oil is believed to be predominantly from the Jurassic Kingak Formation with migration occurring along the basal Cretaceous unconformity.

The dominant trapping mechanism is stratigraphic pinch-out and truncation of the reservoir at an intraformational unconformity along the southern and western flanks of a southeast plunging antiform. Structural dip closure exists along the northern and eastern flanks with a tilted oil-water contact at approximately 6,675 ft (2,034.5 m) subsea. The reservoir sandstones occur within cleaning and coarsening-upward sequences which are interpreted as shallow-marine and sublittoral in origin and deposited as southwesterly trending sand bodies with a provenance to the northeast. Two of the four major lithostratigraphic units mapped exhibit good reservoir characteristics and extend over an area in excess of 200 sq mi (510 sq km).

The cumulative net pay ranges up to 90 ft (27 m) and the estimate of developable oil in place is 4.3 billion stock tank barrels. There is no gas cap.

About 10% of the oil is estimated to be recoverable by primary depletion and it is believed that a further 17% may be recoverable by secondary waterflood. Kuparuk therefore ranks as one of the largest oil fields in the United States. First production is planned for early 1982.

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