Petroleum Systems of Emerging and Future Importance in the Arctic Alaska Petroleum Province

Houseknecht, David W.¹, Kenneth J. Bird², Jonathan Bujak³ (1) U.S. Geological Survey, Reston, VA (2) U.S. Geological Survey, Menlo Park, CA (3) Bujak Research International, Blackpool, England

Arctic Alaska is a world-class petroleum province with significant potential for future discoveries. Most discovered petroleum involves source rocks in the Triassic Shublik Formation or the Cretaceous to Tertiary Hue Shale. Recent discoveries and regional geologic synthesis suggest that future exploration potential may depend on lesser known petroleum systems.

For example, the discovery of the Alpine field drew attention to high gravity oil expelled from the lower Kingak Shale (Early Jurassic). Additional discoveries confirmed the viability of this petroleum system. The Lower Kingak source rock represents a composite condensed section deposited along the southern flank of the Barrow arch. Seismic stratigraphy suggests this source rock has regional extent beneath the southern coastal plain and Brooks Range foothills.

Shelf facies of the Turonian lower Seabee Formation have long been recognized as an oil-prone source rock that is immature or eroded beneath much of the western North Slope. Seismic stratigraphy indicates that the flooding surface beneath the source interval is more regional than previously recognized, extending across the northern Chukchi shelf. Turonian source rocks may be buried into – and locally through – the petroleum window in Tertiary sub-basins offshore.

A Lower Eocene, organic-rich, condensed section dominated by a freshwater fern (Azolla) recently was cored in the Canada Basin. Tongues of this Azolla horizon also occur above flooding surfaces on the eastern North Slope – Beaufort shelf and on the Chukchi shelf, suggesting that a potential source rock is present in Tertiary continental terrace deposits north of the Barrow arch rift shoulder. Although the geochemical characteristics of the Azolla horizon are poorly documented, it is a potential source for Tertiary oil in Beaufort shelf wells and seeps along the coast.