Hydrocarbon flow modeling in complex structures (Mackenzie Basin, Canada)

Abstract

The Mackenzie Basin in northwest arctic Canada has many characteristics of a typical terrestrial, gas-rich sedimentary basin, but the origins of this important hydrocarbon province are still not well known. The three-dimensional basin modeling approach employed here illustrates not only improved capabilities but also potential pitfalls in reproducing flow in complex stratal and structural basin architectures of present-day models. Listric fault structures especially are still inadequately reproduced in most migration models. By integrating individual styles of deformation and introducing a sequence-stratigraphic approach to reproduce the stratal architecture, we are able to identify temporal and spatial relationships between sources and reservoirs. Based on these considerations, three genetic groups of oils in the basin are proposed: a first group mainly related to a Paleocene source rock, a second group related almost exclusively to an early mature source in the Eocene Taglu formation, and a third group related to the Upper Cretaceous Smoking Hills and Boundary Creek formations. In contrast to oil accumulations, gas accumulations resulted mainly from a filling event in the late Miocene, which is interpreted to be related to a decrease in pressure during a late Miocene uplift and erosional event. The Mackenzie Basin is therefore an excellent example to show that the gas proneness of a mature petroleum system, especially if the organic matter is predominantly of terrestrial origin, is mainly a function of expulsion efficiency and timing and thus is directly linked to the structural history of the basin.