(485i) Enhanced Coalbed Methane Via Stimulation of Microbial Biogenesis

Recent microbiological studies have shown that viable methanogenic microbes are still present in water produced from a number of unconventional biogenic gas reservoirs. This suggests the possibility of new methane generation from existing coal deposits (in-situ and in real time), and a renewable source of natural gas. Laboratory results will be presented for a Powder River basin microbial consortium cultured on Wyodak subB coal, along with results for a Surat basin consortium cultured on Walloon coals. For the Powder River basin studies, higher coal-to-methane rates were observed for static versus agitated cultures, indicating that coal surface biofilms may play a critical role. While the addition of complex growth factor substrates (like yeast extract) stimulate overall methane production, they may actually limit the coal bioconversion process. Sulfide serves as a key sulfur nutrient for methanogens, but may be toxic to fermentative species at higher concentrations. Overall, these results support the concept of enhancing coalbed methane reserves by stimulating indigenous microbes. Depending on the rate-limiting factor at a particular site, various reservoir treatment strategies may stimulate this in-situ bioconversion of coal to methane.