New gas material balance to quantify biogenic gas generation rates from shallow organic-matter-rich shales

Coupled laboratory and field investigations resolve microbial interactions that underpin persistence in hydraulically fractured shales

“…The ubiquity of Methanohalophilus across fractured shales ( 2 ) and the high efficiency of methane production demonstrated here indicate that methylamine methanogenesis may be active and important to shale natural gas production. Supporting our findings, a prior study predicted that biogenic methane accounted for 12% of methane produced in a shale-gas well lifetime ( 3 ). Our findings leave open the possibility that the augmentation of fractured shales with exogenous methyl-C1 compounds could enhance biogenic methane production down well, analogous to acetate amendment techniques currently employed in coal-bed methane recovery ( 27 ).…”

“…Recent research suggests that microbial life in shales may impact gas and oil production efficiencies ( 2 , 3 ). For instance, the persistence of methanogens in these ecosystems may contribute to increased biogenic methane formation by Methanohalophilus , while negative impacts, such as corrosion and sulfidogenesis (“souring”), are associated with other prevalent microbial community members including Halanaerobium ( 2 – 9 ). To grow in fractured shales, microorganisms must adapt to increased salinities and reduced chemical conditions where fermentative metabolisms prevail ( 2 ).…”

Enhanced microbial coalbed methane generation: A review of research, commercial activity, and remaining challenges

“…However, drilling and maintaining microbial CBM is becoming less economical due to current, relatively low gas prices and competition from shale gas production, and due to the short life span of CBM production wells (10 years or less; Ayers, 2002;Stearns et al, 2005). Recent laboratory and field experiments have shown that not only has microbial CBM been generated in the geologic past and retained in the formation in commercial quantities, but that some sedimentary basins have active, on-going microbial methane generation (e.g., Cokar et al, 2013;Kirk et al, 2012;Martini et al, 2005;Strąpoć et al, 2007;Ulrich and Bower, 2008). Because methanogenesis is an active process, it may be possible to stimulate the microbial communities that have produced CBM to generate more methane from coal biodegradation on commercially relevant timescales (i.e., years).…”

Biogenic methane and carbon dioxide generation in organic-rich shales from southeastern Brazil

“…Previous efforts to establish the potential of hydrocarbon generation and accumulation in southeastern Brazilian basins focused on the thermal maturation of organic matter (Araújo et al, 2000;EIA/ARI, 2013). However, biogenic methane (CH 4 ) corresponds to more than 20% of natural gas accumulations worldwide (Rice, 1993;Martini et al, 1996) and is also a key component of shale gas production rates of many sedimentary basins of North America (Shurr and Ridgley, 2002;Cokar et al, 2013). Easy monitoring and inexpensive drilling turn biogenic shallow gas systems (Shurr and Ridgley, 2002) in competitive alternatives for shale gas production, since environmental issues such as monitoring of deep aquifers may inhibit shale gas exploration in several countries.…”