Tectono-Stratigraphic Framework of the Permo- Triassic Section in the Prudhoe Bay Area

By

C.E. Paris (BP Exploration (Alaska) Inc.)

A tectono-stratigraphic framework for the Permo-Triassic Section in the Prudhoe Bay area was created to enhance reservoir modeling, infill drilling, and exploration for the reservoirs within this section. The framework was created by incorporating all of the subsurface information available between the Colville and Canning Rivers, including log data from over 2,000 wells, seven 3-D seismic surveys, and core information from over 100 wells.

The Permo-Triassic section in the Prudhoe Bay area contains seven tectono-stratigraphic sequences. The initial transgressive sequence is represented by the Echooka Formation and lower Kavik Shale. This sequence documents the progressive drowning, from southwest to northeast, of the Pre Upper Permian Unconformity, which incised into the underlying Lisburne Group carbonate platform. The subcrop and the onlap pattern of the Pre Upper Permian Unconformity indicate that a tectonic high (the Orion High) existed north of Harrison Bay, and a second high (the Mikkelson High) existed northeast of the Prudhoe Bay Unit, during Permo-Triassic time. These tectonic highs were the source areas for the siliciclastic deposits of the upper Kavik Shale and Ivishak Formation. The Kavik Shale and Ivishak Formation contain four deltaic-fluvial sequences and a forced regression sequence, which are strongly controlled by the tectonic activity of these highs. This section is capped by a widespread early rift/extensional sequence represented by the Shublik and Sag River Formations.

AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.