Extent and limits of biodegradation by in situ methanogenic consortia in shale and formation fluids

Acetate, DIC and δ13CDIC evidence for acetoclastic methanogenesis in Songliao Basin, NE China

“…Patchy microbial activity associated with the fracture zone may be still going on, however, overall biogenic gas generation potential is low. Similar conclusion for overall low microbial activity in shale system has been draw by other studies (Gao et al, 2013;Schlegel et al, 2013).…”

“…High acetate concentrations in extracted water samples may prove acetate fermentation is limited. Previous studies suggested that acetate concentrations 45 μM indicate inhibited acetoclastic methanogenesis (Lovley and Phillips, 1987;Schlegel et al, 2013). Although our data is difficult to correlate with published value due different analytical methods, large difference between different areas may suggest variable microbial activities.…”

The biogenic methane potential of European gas shale analogues: Results from incubation experiments and thermodynamic modelling

“…Even if the rock possesses sufficient theoretically bioavailable organic substrates, the development of a methanogenic microbial community (including methanogenic Archaea and accompanying fermenting microflora) can be hindered if there are no pores big enough, fractures or other spaces for microbiota to grow (Schlegel et al, 2013). The absence of an active community in the Wealden samples could be related to that fact.…”

“…Conversely, Posidonia (particularly Harderode) and Alum shale samples would contain an active hydrocarbon-degrading methane-producing community. The actual current in situ transformation of residual hydrocarbons to methane and CO 2 , however, will eventually rely on other factors such as current temperature, availability of water, salinity, N, P and other micronutrients, listed by Schlegel et al (2013). On the other hand, the presence of toxic substances could inhibit microbial growth, whereas at sulphate concentrations high enough (Siegert et al, 2011) methanogens would probably be out-competed by sulphate reducers.…”

Methanogenic microbial community of the Eastern Paris Basin: Potential for energy production from organic-rich shales

“…The distribution of aquifers and aquitards has a major control on fluid migration in sedimentary basins . Meteoric waters allow an increasing dilution of basin brines from the center to the margins, which impacts the yield and pathway of microbial methanogenesis (Martini et al, 1998;McIntosh et al, 2008;Schlegel et al, 2013) as well as the diversity and distribution of methanogenic archaea (Waldron et al, 2007). The microbial mineralization of OM into CH 4 in these shallow biogenic gas systems relies on the cooperation of different groups of anaerobic microorganisms.…”