Microbial Community Dynamics in the Hydraulic Fracturing Water Cycle from Two Newly Fractured Shale Gas Wells in the Duvernay Formation, Alberta

  • Author / Creator
    Zhong, Cheng
  • The microbial ecology of the hydraulic fracturing water cycle may influence the efficiency of shale gas production and strategies for water reuse and treatment. In this study, microbial community dynamics were tracked by sequencing of 16S rRNA genes coupled with enumeration of live/dead cells in flowback and produced water (FPW) from two newly fractured Duvernay shale oil and gas wells (112-115C). For both wells sampled, I found that numbers of total cells, microbial diversity and richness were considerably reduced, the highly diverse initial freshwater communities rapidly shifted to become dominated by halotolerant genus Halanaerobium, and subsequently DNA was insufficient for sequencing. Moreover, lower cell viability, microbial diversity, and faster enrichment in Halanaerobium were observed in the early period of FPW from the well that used recycled produced water (RPW). Furthermore, I discovered in a separate experiment that adding 10% RPW in freshwater quickly enriched Halanaerobium, and fostered other heterotrophic genera affiliated to the class Alphaproteobacteria before injection. My results have implication of microbial ecology in high temperature brine may not consistent with low temperature brine, the predominance members of Halanaerobium may pose a risk of detrimental impact from microorganisms downhole, and undesirable bacteria may alter original freshwater communities before fracturing due to FPW recycling.

  • Subjects / Keywords
  • Graduation date
    Fall 2017
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.