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The Breakup of the Supercontinent Rodinia and Its Importance in Finding and Developing a CCS Site in the Illinois Basin

Leetaru, Hannes E.*1; McBride, John H.2
(1) Illinois State Geological Survey, University of Illinois, Champaign, IL.
(2) Geology Department, Brigham Young University, Provo, UT.

The Cambrian Mt. Simon Sandstone is the most important carbon sink available for the sequestration of CO2 in the heavily industrialized Midwest of the United States. The workflow in finding and characterizing a CCS site in the Illinois Basin can be improved by understanding the impact of the Precambrian breakup of the supercontinent Rodinia on the geology of the Mt. Simon Sandstone. In the Illinois Basin region, the Rodinia breakup appears to have formed a rift basin that provided accommodation space for over 2600 feet (792 meters) of Mt. Simon siliciclastic sediments. Areas outside the proposed rift basin have significantly thinner Mt. Simon and can be influenced by Precambrian topography where the Mt. Simon sandstone is either thin or non-existent. Reflection seismic sections suggest that the thickening of the Mt. Simon was controlled by contemporaneous faulting that formed during the rifting. The Mt. Simon is thicker on the downthrown side of these faults.

Wells at the US DOE-funded Illinois Basin - Decatur Project in Macon County, Illinois encountered the best reservoir quality rocks in alluvial fan and braided river deposits of the lower Mt. Simon. These lower Mt. Simon rocks had average porosities of 22% and permeabilities of 200 mD. However individual intervals had porosities as high as 28% and permeabilities of over one Darcy. Regional mapping suggests that these lower Mt. Simon reservoirs are more prevalent within the rift. Both seismic reflection data and well control suggest that the braided river deposits formed significant lateral and vertical reservoir heterogeneity that may complicate predicting the migration of any CO2 plume.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California