INVESTIGATING THE GEOCHEMISTRY AND MICROBIOLOGY OF NATURALLY OCCURRING CARBON DIOXIDE IN SEDIMENTARY BASINS IN THE UNITED STATES

Carbon dioxide (CO₂) is one of the primary greenhouse gases emitted naturally from the earth’s surface and from anthropogenic stationary sources. In 2013, the United States emitted 5,393 million metric tons of CO₂ as a result of coal, natural gas, and petroleum consumption. The USGS Carbon Sequestration Geologic Research and Assessments Project is currently evaluating natural CO₂ reservoirs as analogues for CO₂ storage and as resources for CO₂-enhanced oil recovery. Evaluation of natural CO₂ reservoirs as analogues for geologic CO2 storage will potentially lead to developing tools to predict the geochemical and environmental effects of storing anthropogenic CO₂ in geologic reservoirs.

Currently, detailed studies of natural CO₂ reservoir analogues are focusing on reservoirs with at least 10 % CO₂ gas composition. To date water, and gas samples have been collected for compositional, isotopic, and microbial analyses from CO₂ wells and hot and cold springs in Santa Maria Basin, California; Ventura Basin, California; Gulf of Mexico Basin, Mississippi; Wyoming Idaho Utah Thrust Belt, Idaho, Wyoming, and Utah; Uinta Basin, Utah; Greater Green River, Wyoming; Ventura Basin, Eastern Great Basin, Utah; and the Paradox Basin, Utah. Geochemical and microbial analyses of water samples collected from wells and springs producing CO₂ will be used to determine the geochemical effects of CO₂ on reservoir fluids, and the rate of CO₂ dissolution into reservoir formation waters. All data, including legacy data, will be merged into a robust dataset, which will provide valuable information on CO₂ geochemistry and microbiology in natural CO₂ reservoirs, and will provide useful information to industrial and scientific communities interested in anthropogenic CO₂ storage.