The Chukchi Sea Planning Area, Alaska: Structural Development, Basin Analysis and Hydrocarbon Potential

Abstract

Seismic stratigraphic and seismic fault evidence both show that the Central Chukchi basin is a north-trending, fault-controlled basin, which developed at the beginning of early Mississippian time. About 20 km thickness of sediments have been deposited in the basin. Using a simple flexural model a series of 3-dimensional basement motion patterns with time was produced. From these characteristic patterns two stages of basement evolution can be recognized: the first is basement subsidence controlled by regional extensional fault systems during the period from early Mississippian to later Jurassic: the second stage is basement evolution as two nearly separate blocks from the beginning of Early Cretaceous. The west block development is related to reactivation of the old fault system, while the subsidence of the east block is caused by tectonism and associated sediment loading due to progressive thrusting northward of the Brooks Range. Quantitative basin modeling techniques show that many uncertainties occur when applying mathematical and computer models to simulate a sedimentary basin, especially in a frontier area where only limited data are available. In this study, quantitative basin modeling techniques applied to the Chukchi Sea Planning Area, Alaska, demonstrate how uncertainty can be handled. The Chukchi Sea Planning Area encompasses about 127,000 square kilometers of the northwestern Alaska continental shelf and lies offshore of the Natural Petroleum Reserve in Alaska. Only seismic data and a few remote onshore wells are available in the Planning Area. Compared with the North Slope of Alaska, the Planning Area has had a significantly different structural history. In addition, most of the strata in the Area are currently thermally mature to overmature and in the stage of generating dry gas. The prospective areas for oil are the margins of the central Chukchi Basin, such as the Chukchi platform, Herald Arch and northeast part of the basin.