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Kevin Dome, Montana: Reservoir Characterization of a Natural Analog for CO2 Sequestration and Its Significance for Evaluating Similar Structural Features in Montana

Bowen, David W.1; Lageson, David R.1; Jackson, Frankie D.1; Eby, David E.2
1 Earth Sciences and Energy Research Institute, Montana State University, Bozeman, MT.
2 Eby Petrography and Consulting, Inc., Denver, CO.

Kevin Dome, located in Toole County, Montana is a very large structural culmination along the north-trending Sweetgrass Arch. The dome covers approximately 700 square miles with approximately 750 feet of structural relief. Naturally occurring CO2 has been documented from several oil and gas wells that have tested the Duperow Formation over the past 50 years, but the volume, continuity of the trapped gas, and circumstances of its entrapment have been poorly understood. Below gas (CO2) / water contacts in individual trapped reservoirs on Kevin Dome, the Duperow Formation is also a saline aquifer having very poor water quality (greater than 10,000 ppm TDS). The combination of a natural trap ensuring caprock efficacy and formation compatibility with CO2, the large volume of this static trap, the poor quality contained water, the proximity to present and future sources of anthropogenic CO2, and the similarity of this feature to other large domes in Montana determine this geologic feature to have great regional significance for understanding sequestration potential and capacity.This study details the stratigraphic framework across Kevin Dome with an emphasis on reservoir characterization of the CO2 bearing Duperow Formation. A grid of correlation cross-sections was constructed to provide a stratigraphic framework of reservoir and caprock units. This framework constrained well-log correlations used to construct more detailed structure contour and isopach maps of critical units on Kevin Dome and to provide the framework within which more detailed facies analysis of the Duperow Formation was accomplished. Cores of the Duperow Formation on Kevin Dome and from surrounding areas, and outcrops of the Duperow south and west of Kevin Dome were described and sampled for microscopic analysis. Data from both drill stem tests and production tests of the Duperow Formation were analyzed to determine the distribution of CO2 in the Duperow Formation and its distribution within specific porosity zones and at specific structural datums. This data was analyzed to better understand the potential for commercial scale sequestration in the Kevin Dome region and to produce CO2 sequestration capacity estimates. The conclusion is that Kevin Dome and the surrounding region has a large potential capacity for CO2 sequestration. The work also demonstrates substantial promise that other similar geologic features in Montana have the potential to sequester large volumes of CO2.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009