2014 Rocky Mountain Section AAPG Annual Meeting

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Assessing the Carbon Sequestration Potential within the Bear River Formation of the Wyoming-Idaho-Utah Thrust Belt


The United States Geological Survey (USGS) was directed by the 2007 Energy Independence and Security Act to assess the potential geologic storage resources for carbon dioxide (CO2) within the United States. Utilizing its probabilistic methodology for a national CO2 geological sequestration assessment, the USGS has assessed the storage potential of the shale and sandstone dominated Cretaceous Bear River Formation within the Wyoming-Idaho-Utah (W-I-U) thrust belt. The basic assessment unit used in the USGS methodology is the Storage Assessment Unit (SAU), which consists of a storage formation and an overlying regional seal formation. The SAUs are defined by geologic criteria that include rock properties, formation depth, and regional extents of the storage and seal formations. The methodology requires that the storage formation be porous and permeable, and at depths of 3,000–13,000 ft below ground surface to ensure that CO2 will remain in a supercritical phase. In some instances, thrusted Bear River Formation overlies a repeated, deeper section of Bear River Formation and rock properties indicate that CO2 could be stored at depths greater than 13,000 ft, in a separate “deep” SAU. The storage formation and overlying seal are required to be continuous and regional in extent. Within the W-I-U thrust belt, there are thick, regionally extensive, marine shales (Aspen and Mowry Shales) which could inhibit the flow of buoyant CO2 into overlying strata. This USGS carbon sequestration assessment has shown that there is potential for CO2 sequestration within the structurally complex Cretaceous Bear River Formation of the W-I-U thrust belt.