MOLECULAR SEQUENCES DERIVED FROM PALEOCENE FORT UNION FORMATION COALS VS. ASSOCIATED CO-PRODUCED WATERS IN THE POWDER RIVER BASIN: IMPLICATIONS FOR CBM REGENERATION STRATEGIES

The objective of this study is to determine if there are differences between methane-producing organism nucleic-acid sequences associated with Fort Union Formation subbituminous coals in the Powder River Basin, Wyoming and sequences that can be recovered from associated CBM co-produced waters. Contemporary aquifer-derived methanogens from coalbed methane (CBM) co-produced waters have been used in most studies of CBM regeneration. Nutrients and complementary energetic constituents (oxidants, reductants, etc.) usually are added to allow methanogenesis to take place and regenerate gas. For this study, coal cores and filtered organic matter samples from the co-produced waters were collected from CBM drill holes targeting the Wyodak-Anderson coal-bed reservoirs, which account for 70% of the total gas production in the basin. Based on our results obtained from this study, it appears that there is a wider range of molecular sequences related to known methanogens associated with the coal beds, which are different than in the associated co-produced waters. Those in coal beds include Methanobacterium thermoaggregans, Methanospirillum hungatei, Archeoglobis fulgidus, and Methanopyrus kandleri, while molecular sequences observed in the co-produced waters include sequences related to Methanocaldococcus vulcanus, Methanothermococcus sp. Ep70, and Methanomicrobium mobile. Thus, molecular sequence variations indicate that indigenous methanogen sequences associated with coals might be different from those associated with aquifers and other contemporarily impacted environments, suggesting that different strategies may be needed to stimulate methane regeneration processes in these subbituminous coal reservoirs than might be used in managing aquifer-associated microbial communities.