47th Annual AAPG-SPE Eastern Section Joint Meeting

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From the Tuscarora Sandstone to the Bubbles in Your Beverage: Naturally- Occurring CO2 in the Indian Creek Field, Kanawha County, WV.


The Tuscarora Sandstone in the Indian Creek field produces commercial volumes of food-grade carbon dioxide (CO2) as a constituent of the natural gas stream. Presence of naturally-occurring CO2 presents a unique opportunity to examine an analog for long-term carbon storage, but the mechanisms of its generation and trapping are not fully understood. As part of a research project funded by the U.S. Department of Energy, geoscientists from Battelle Memorial Institute and the West Virginia Geological Survey examined thin sections, well logs, drilling and completion reports, and core from wells inside the Indian Creek field and compared these data to wells from nearby fields that do not produce significant amounts of CO2 in gas accumulations. Geologic cross-sections and isopach maps of the Tuscarora were augmented with Computed Tomography (CT) scans of the cores to assess potential fracture networks and migration pathways. Pores in thin sections of Tuscarora taken from a well drilled inside the field exhibit thin, incomplete, linings of calcite that appear to be an early cement partially dissolved by later pore fluids to produce CO2. A second possibility for CO2 generation is suggested by the presence of pores lined with framboidal pyrite typically associated with bacterial degradation of organic matter such as hydrocarbons. Thin sections taken from a core outside the Indian Creek field are characterized by bedding-parallel stylolites, often filled with heavy minerals and/or clays, as well as thick quartz overgrowths, and sutured grain contacts. Sediments in this core are burrowed; the burrows are backfilled with very fine to silt-sized quartz. Porosity is fracture-enhanced and contained within burrows rather than the matrix. Though there are multiple areas of gas production from the Tuscarora Sandstone, commercial production of the CO2 is unique to the Indian Creek field in the Appalachian basin, providing a natural laboratory for the effects of potential carbon storage.