Sequence Stratigraphic Analysis of the Kuparuk River Field: Implications for Kemik Exploration on the North Slope of Alaska

A. D. Donovan, D. J. Bouquet, P. E. Walker, L. M. Dobson, and M. D. Sullivan

A detailed sequence stratigraphic analysis of the Kuparuk River Field on the North Slope of Alaska reveals that the distribution, thickness, and facies variations of the Early Cretaceous Kuparuk A and Kemik (Kuparuk C) reservoirs are controlled by the primary depositional paleogeography of these units, as well as their post-depositional erosion and accommodation patterns. The Kemik stratigraphic interval at the Kuparuk River Field is an unconformity-bounded depositional sequence. This sequence consists of a basal aggradational to retrogradational portion, interpreted as the lowstand and transgressive systems tracts, overlain by a progradational portion interpreted as a highstand systems tract. The distribution and thickness of the underlying Kuparuk A reservoirs are also effected by the Base and Top Kemik unconformities, as well as by four unconformities located within and at the top of the Kuparuk A.

Within this sequence stratigraphic framework, Kuparuk A and Kemik reservoirs are interpreted as erosional remnants of, what were originally, more laterally continuous highstand and transgressive shorelines, and lowstand incised valley systems. Kemik and Kuparuk strata were preserved in paleo-structural lows and eroded over paleo-structural highs formed during Early Cretaceous deformation. This syn-rift deformation coincided with the development of the base Kemik and top Kemik unconformities. Sequence-keyed paleogeographic maps across the Kuparuk River Field, reveal that: 1) Kemik highstands were deposited along an arcuate-shaped, low-energy, wave-dominated shoreline which, in general, becomes more proximal to southwest and more distal to the northeast; 2) Kemik incised valleys (lowstands) trend, in general, NE-SW and thicken to the northeast; and 3) Kuparuk A reservoirs, unlike the Kemik, prograded and were derived from the north.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California