METAGENOMIC INSIGHTS INTO MICROBIAL PROCESSES IN PERMIAN BASIN PRODUCED WATERS

As unconventional oil and gas production continue to be a major domestic source of energy, interest in the biogeochemistry of these hydraulically fractured environments has increased. The microbial community that reside within these environments can catalyze geochemical reactions such as scaling, corrosion, and fouling. Potential negative effects include infrastructure failure, plugged hydraulic fractures, gas/oil drainage from communication with nearby wells, and methane/fracture fluid leakage. Recent studies have shed light on the microbial community inhabiting many of these unconventional reservoir environments and the correlating geochemistry. However, the Permian Basin is the top hydrocarbon producing basin in the United States, and the relationship between the geochemistry and microbiology of Permian Basin produced waters remains unestablished. Here, we present the geochemistry and microbiology of 9 produced water samples taken from a Permian Basin unconventional reservoir. Groundwater used for fracturing operations was also sampled. Molar geochemical relationships (Cl:Br) demonstrate a distinct dilution effect on produced waters caused by injection fluid. Dissolved sulfate values were higher in produced waters with lower TDS (>100,000 mg/L), suggesting injection fluid may provide a unique niche for microbial activity. Results from shotgun metagenomic sequencing suggest a potential for corrosion, fouling, and souring events in the oilfield. Ten metagenome assembled genomes were recovered, and reconstructed pathways indicate a potential for classical sulfate reduction, thiosulfate reduction, biological methane production, and biodegradation of aromatic compounds. Results from this study show produced waters from oil and gas extraction to represent unique microbial ecosystems, hosting rare microbial taxa and processes that will affect production procedures and produced water management. These findings also expand the current understanding of the microbial ecology in hydrocarbon environments and may aid in the development of more specific and efficient biocide treatments, with the goal to improve operational efficacy and safety.