University of Maryland at College Park; Department of Geology
College Park, Maryland
Geologic storage of CO2 in depleted natural gas fields is one mitigation option for reducing the amount of emitted anthropogenic CO2. Analog studies of high-CO2 gas fields, containing greater than 10 wt.% CO2, are useful to better understand the potential long-term mineralogical and geochemical effects inherent in geologic CO2 storage. One such analog exists in the Kanawha County, WV, Indian Creek natural gas field that has a mean of 65 wt.% CO2. The gas reservoir is the lower Silurian Tuscarora sandstone, a medium to coarse-grained, well-rounded, pure orthoquartzite that is dominated by secondary fracture porosity. Over 40 samples obtained from a continuous well core of the Tuscarora will be compared to similar lithologies from outside of the high CO2 field to determine differences in texture, composition, and mineralogy. This comparison is expected to show the effect of high CO2 concentrations on a subsurface reservoir body by applying various petrographic and fluid inclusion techniques. Possible changes in the Tuscarora from the high of CO2 concentrations might include modifications to cementation, porosity, and mineralogy. Since the Tuscarora is typically tightly cemented, this study will focus on conditions that prevented overgrowth formation, including the paleo-locations of trapped gas pockets, where clay overgrowths on quartz, and near secondary fracture networks. Because no other analog studies within the Appalachian basin have been done, this analog study will provide first order information that can be applied to local reservoirs within the Tuscarora and similar lithologies for the purpose of geologic storage of CO2 in the subsurface.
AAPG Search and Discovery Article #90033©2004 AAPG Foundation Grants-in-Aid