S76: Microbial Composition Analysis in Environments Associated With Energy Production

Waterflooding and hydraulic fracturing are predominately used technologies in hydrocarbon energy production. Water from various sources, together with organic and inorganic additives, is injected into energy reservoirs to help drive oil and natural gas out.  As a result, new microorganisms can be introduced and adapted to these subsurface environments, and abundant microbial food in injection water can stimulate subsurface native microbe growth, which can eventually result in microbial community changes in these subsurface habitats and downstream environments. Several case studies of microbial compositions in various water samples collected from energy production environments, demonstrated that microbial compositions varied significantly among these samples. In two of these studies, DGGE and/or qPCR were used to monitor bacteria and archaea diversity changes in water samples from different stages of a hydraulic fracturing process. It was found that microbial diversity in flow back water was different from that in fracturing water and changed with time and geochemical conditions. In another study, pyrosequencing analysis of water samples from different sources within  oilfield water management systems showed that sulfate reducing bacteria (SRB) dominated in most water sources, but also that the dominant SRB species in the produced water were different from that presented in the above ground water management systems. Results presented in this paper illuminate that waterflooding and hydraulic fracturing operations can change microbial ecology in subsurface and associated environments. Microbial composition analysis can also help in developing the right microbial control strategies for effective energy production.