4-D Modelling of Offshore Carson Basin, Grand Banks, Eastern Canada

J. B. W. Wielens, C. D. Jauer, and G. L. Williams
Geological Survey of Canada Atlantic P.O. Box 1006, Dartmouth, NS, B2Y 4A2 email: [email protected]

There are several barely explored basins on the Grand Banks, which have hydrocarbon potential. The shelf-slope Carson Basin in the southeastern part of the area is one of them. The basin contains a sequence of Triassic to Tertiary/Quaternary strata that includes reservoirs, seals and a thick salt section. Source rock was not found by the four wells drilled on the eastern, high flank of the basin, but a strong case can be made for the presence of an Early Kimmeridgian one in the deeper part of the basin. Postulating a conservative 50 m thickness, 4% TOC and 600 HI, it has the potential to generate 100 billion barrels of oil. The early-late Cretaceous Avalon Uplift caused deep erosion into the underlying section. Salt moved from Jurassic through Paleogene times, forming diapirs and massive salt walls with associated structures. A model constructed from new biostratigraphic analyses, four seismic surfaces, and pertinent geological data was simulated with the IES Petromod software program. The results show a viable petroleum system with significant hydrocarbon potential. In the model, petroleum generation was driven primarily by the increased heatflow to about 100 mW/m2 during the rifting of Grand Banks and Iberia, between 125 and 68 Ma and it stopped thereafter. Thus, any of the structural traps formed later will have low filling potential. The simulation implied that mainly stratigraphic traps were filled. Heatflow is the main uncertainty. Models run at 60 mW/m2 without increased rifting heatflow show that the basin could still generate significant, but smaller, quantities of hydrocarbons from 90 Ma to present. A live 4-D model will demonstrate these points.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005