Analysis of the Beaufort-Mackenzie Basin, Canada: burial, thermal and hydrocarbon histories

Abstract

The burial, thermal and hydrocarbon histories of Jurassic-Tertiary sedimentary successions were investigated for three structural zones of the Beaufort-Mackenzie Basin using a one-dimensional comprehensive burial history model. The reconstructed geohistories of seven wells indicate two stages of tectonics in the study area: (1) rifting from the Jurassic to Early Cretaceous in structural Zone I and subsequent extension in structural Zone II; and (2) uplift and erosion after rifting, as well as thermal subsidence. The maximum burial of Jurassic-Cretaceous and Tertiary sediments corresponds to the rifting episode. The Late Eocene to Late Miocene uplift caused at least 1000 – 2000 m of sediment to be removed in the study area. The Late Miocene to Pleistocene thermal subsidence resulted in an accumulation of thick fluvial delta sediments (the Iperk sequence) from the Mackenzie Delta to offshore of the Beaufort Sea. Heating episodes from around 150 to 20 Ma in the Tuktoyaktuk Peninsula province and from around 60 to 10 Ma in the central and western part of the basin are indicated by the inversion of vitrinite reflectance data from seven wells. Comparison of the thermal maturation pattern with oil and gas occurrences in seven of the wells indicates that hydrocarbons in Cretaceous reservoirs may have migrated vertically from the Husky Formation, whereas the hydrocarbons in the Tertiary reservoirs may have undergone extensive lateral migration from offshore, where the Richards sequence source rock has a deeper burial history than onshore.