Microbes in the Marcellus Shale: Distinguishing Between Injected and Indigenous Microorganisms

Abstract

Hydraulic fracturing is the industry standard for extracting hydrocarbons from shale formations. While several studies have demonstrated microbial activity in fluids from hydraulically fractured wells, it is not known if these microbes are indigenous to the deep subsurface before energy extraction. Here we compare the microbial communities in fluids used during drilling and hydraulic fracturing to those in pristine sidewall cores from the Marcellus Shale Energy and Environment Laboratory (MSEEL) in Morgantown, West Virginia. Fluid samples included drilling muds, source water in hydraulic fracturing fluids (Monongahela River water, recycled produced fluids), and fracturing fluids. Fluids were filtered to collect microbial biomass. Sidewall cores were collected from a 360-foot span within the MIP-3H well in the Genesseo, Tully, Mahantango, Marcellus and Onondaga formations. After collection, cores were surface sterilized (verified by microscopy to confirm removal of 0.5 μm fluorescent microsphere tracers), ground, and homogenized before DNA extraction. Initial analyses of DNA extracted from drilling muds show that the microbial community contains the functional capacity for fermentation of hydraulic fracturing chemical additives, sulfide production, creation of biofilms and the production of methane. These metabolisms could allow injected microorganisms to thrive in the subsurface, with both negative and positive effects on the energy extraction process. Ongoing analyses of microbial communities in the remaining fluid and shale samples will ultimately identify the indigenous and introduced microbes in these formations. This is the first study of its kind to distinguish between indigenous microorganisms and those injected in the deep subsurface by the process of hydraulic fracturing. Genomic reconstruction of injected and indigenous microbes will allow us to identify metabolic pathways and adaptations that define microbial roles in hydrocarbon reservoirs, before and during energy extraction.

AAPG Datapages/Search and Discovery Article #90258 © 2016 AAPG Eastern Section Meeting, Lexington, Kentucky, September 25-27, 2016