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Sequence Stratigraphic and Geodynamic Evaluations of Alaska North Slope Petroleum Elements within a 3D Earth Model

E. Wong, J. L. Etienne, K. Evans, N. Harvey, R. Martin, and L. Robinson
Neftex Petroleum Consultants Ltd., Abingdon, United Kingdom

Arctic Alaska is one of the most petroliferous provinces in North America although only a small part of it has been thoroughly explored. Hydrocarbon exploration has concentrated on Beaufortian strata (Jurassic – Lower Cretaceous) which were deposited during the rifting of Northern Alaska away from Arctic Canada. During the rifting phase and opening of the Arctic Ocean Basin, mud-dominated Beaufortian sediments accumulated in both basinal and shallow marine settings. These syn-rift deposits contain both working source rocks and reservoir rocks of the North Slope.

Four key source rocks of Alaska North slope were assessed in this study – the Triassic Shublik Formation, the Jurassic Kingak Shale, the Cretaceous ‘pebble shale’ unit and the Hue Shale. By using spatially enabled geochemical data from our global petroleum systems database we have been able to define the potential depositional extent of these organic-rich facies. Thermal maturity data coupled to depth maps have also been used to further refine regional kitchen maturity. The stratigraphically complex nature of the North Slope requires the need of a regional sequence stratigraphic framework and geodynamic plate reconstruction to enhance the evaluation of paleoenvironment and tectonic elements associated with the break-up event. This application can aid a better understanding of the regional petroleum systems.

By combining an expansive sedimentological, geochemical and biostratigraphic datasets in the public domain, we developed a proprietary global sequence stratigraphic model based on 3rd order biostratigraphically constrained maximum flooding surfaces and sequence boundaries. Petrel 2011* enables us to build 3D geological models at a scale appropriate for regional exploration. We load and manipulate the sequence stratigraphically calibrated geoscience information, seismic and other data from the NPRA in Petrel 2011 to visualise source rock, reservoir and seal facies in both depth and geological time domains. This not only improves efficiencies, but adds increased insight into the geological basis for petroleum system and play fairway analysis.

Visualisation in a 3D model enables a more thorough analysis of existing and potential hydrocarbon plays within a structurally complex region such as the North Slope Alaska. Results from this area may serve as good analogues to the frontier regions of Beaufort and Chukchi Sea in the absence of high density data.

AAPG Search and Discovery Article #120098©2013 AAPG Hedberg Conference Petroleum Systems: Modeling the Past, Planning the Future, Nice, France, October 1-5, 2012