How Specific Microbial Communities Benefit the Oil Industry: Anaerobic Microbial Processes and the Prospect for Methane Production from Oil

Abstract

In strict anaerobic environments, oxygen is essentially non-existent. However, anaerobic microorganisms may thrive in such environments by metabolising organic or inorganic energy and/or carbon sources while respiring alternate electron acceptors such as nitrate, metals, or sulphate. Methanogenesis is the key electron accepting process in environments characterised by the absence of any electron acceptors other than CO₂. Geological evidence has shown that most of the Earth’s petroleum resources have been biodegraded over millennia, the extents to which likely depended on nutrient and water availability, temperature, and the requisite microorganisms (Röling et al., 2003; Head et al., 2003; Hallmann et al., 2008). Gases of biological origin including methane are believed to be primary byproducts of microbial oil metabolism in petroliferous deposits where oil quality has diminished due to the preferential consumption of valuable ‘light’ hydrocarbons (Head et al., 2003; Milkov and Dzou, 2007; Jones et al., 2008). While this phenomenon has enormous economic implications for recovering high-value light oil, it also sets the precedent for a potential alternate energy recovery strategy – that is, recovering energy as methane gas that is biologically produced as the result of methanogenic oil biodegradation in petroleum reservoirs that are at their economic limits.