Sunday, April 29, 2007

Stimulation of methanogenic consortia associated with shallow methane producing aquifers

Patrick C. Gilcrease, Keith C. Flanegan, and Michael S. Green. Dept. of Chemical and Biological Engineering, South Dakota School of Mines and Technology, 501. E. St. Joseph Street, Rapid City, SD 57701

Field samples from shallow biogenic gas producing aquifers in Wyoming and South Dakota (Powder River Basin and the Dolton aquifer, respectively) have tested positive for the presence of living microbial communities capable of producing methane (methanogenic consortia).   If these communities are capable of producing methane from organic sources present in the reservoir (coal or shale), this suggests an opportunity to maintain or enhance methane reserves in these aquifers by maintaining/enhancing the activity of existing methanogenic consortia in-situ.   In this study, consortia indigenous to these reservoirs were cultured in the laboratory; the Powder River Basin and Dolton consortia were shown to produce methane with Wyodak coal and Dolton aquifer shale as the sole carbon substrate, respectively.   In further studies with the Powder River Basin consortium, methanogenic activity was measured as a function of various environmental variables such as temperature, pH, and supplemental nutrients.  The effect of environment on methanogenic activity will be discussed, along with implications for reservoir management in producing aquifers.