Thermal History and Hydrocarbon Maturity Study in the Norton Basin, Alaska

Abstract

Two COST wells in the Norton Basin of Alaska were examined using a one-dimensional quantitative dynamic model (1-D). By inversion of vitrinite reflectance data with the present day thermal gradient in the basin, the paleothermal history of the basin was reconstructed and showed two high thermal peaks, one during the initial stage of basin development (60–50 MaBP) and the other at late Miocene (15–5 MaBP). The early thermal peak corresponded to thinning of the lithosphere and subsidence with upwelling of the hot asthenosphere, and the more recent thermal high was caused by the subsidence and volcanic activity during late Miocene. The Norton Basin is thermally mature with hydrocarbon generation occurring in 15–2 MaBP. Modeling the fluid flow and geopressure development using a two-dimensional fluid flow/compaction model in the basin shows that the directions of fluid movement are both vertical and towards the Yukon Horst, a main horst structure in the basin, suggesting that the hydrocarbons might accumulate in structures around the Yukon Horst and in stratigraphic traps within the basin, which are expected to be common because of the depositional variation of the various facies.