Microbial communities in freshwater used for hydraulic fracturing are unable to withstand the high temperatures and pressures characteristic of fractured shales

Sophie Nixon, Alvaro M. Plominsky, Natali Hernandez Becerra, Christopher Boothman, Douglas H. Bartlett

Research output: Contribution to journalArticlepeer-review

Abstract

Natural gas is recovered from shale formations by hydraulic fracturing, a process known to create microbial ecosystems in the deep subsurface. Microbial communities that emerge in fractured shales include organisms known to degrade fracturing fluid additives and contribute to corrosion of well infrastructure. In order to limit these negative microbial processes, it is essential to constrain the source of the microorganisms responsible. Previous studies have identified a number of potential sources, including fracturing fluids and drilling muds, yet these sources remain largely untested. Here, we apply high pressure experimental approaches to assess whether the microbial community in synthetic fracturing fluid made from freshwater reservoir water can withstand the temperature and pressure conditions of hydraulic fracturing and the fractured shale environment. Using cell enumerations, DNA extraction and culturing, we show that the community can withstand high pressure or high temperature alone, but the combination of both is fatal. These results suggest that initial freshwater-based fracturing fluids are an unlikely source of microorganisms in fractured shales. These findings indicate that potentially problematic lineages, such as sulfidogenic strains of Halanaerobium that have been found to dominate fractured shale microbial communities, likely derive from other input sources into the down well environment, such as drilling muds.
Original languageEnglish
JournalAccess Microbiology
Volume5
Issue number4
DOIs
Publication statusPublished - 21 Apr 2023

Keywords

  • Hydraulic fracturing
  • high pressure
  • fractured shale microbial communities
  • fracturing fluid additives

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