SEISMIC STRATIGRAPHIC ANALYSIS OF THE NANUQ SOUTH 3D SEISMIC SURVEY, CENTRAL NORTH SLOPE ALASKA

The Colville Basin in the Central North Slope, Alaska is a foreland basin formed during the Late Jurassic and Early Cretaceous Brooks Range orogeny as a result of collision between the Koyukuk Island arc and a Devonian-to-Jurassic south facing passive margin. The basin houses many prolific oil and gas fields and contains four major tectono-stratigraphic units, from oldest to youngest: Franklinian, Ellesmerian, Beaufortian, and Brookian. The Brookian Sandstone reservoirs in the Nanushuk and Torok Formations have been the primary targets for oil production. We conduct seismic stratigraphic analysis of the Beaufortian and Brookian sequences. The analysis is based on our interpretation of the Nanuq South 3D seismic survey data in the Central North Slope.

Our preliminary interpretations suggest that the Beaufortian sequence is represented by parallel and subparallel reflections that indicate uniform accumulation rates on a stable basin plain setting. The Brookian sequence is represented by prograding reflections that contain major depositional discontinuities such as topset, foreset, bottomset, and clinothems of a typical deltaic sedimentary succession. The reflections are interpreted as strata where significant deposition occurred due to lateral progradation of a deltaic sequence. The nature and geometry of the sequences will be used to determine structural/tectonic control on the sedimentological and stratigraphic evolution of the area and its surroundings.