Temporal Changes of Sulfate-Reducing Microbial Communities Based on Functional Gene Sequencing in Production Water of Shale Gas Reservoir

Microbial sulfate reduction is a crucial metabolic process in shale gas reservoirs and a major contributor to microbiologically influenced corrosion (MIC). To better understand and control the corrosion of sulfate-reducing bacteria (SRB) during repetitive fracturing in produced water. In this paper, dissimilatory sulfite reductase (dsrB) gene sequencing and quantitative real-time PCR (qPCR) techniques were used to compare SRB communities in flowback and produced water from two shale gas wells (QS: fracturing with fresh water, FP: fracturing with produced water) in the Changning area of the southern Sichuan Basin at multiple time points. A total of 10 samples from the QS and FP wells were analyzed, revealing a shared core species distribution of Archaeoglobus (28.12%), Desulfomicrobium (10.75%), and unclassified_d_bacteria (18.97%). The dominant genus in well QS was Archaeoglobus, while well FP was unclassified_d_bacteria. The number of SRB was consistently higher in well QS compared to well FP throughout the production process. Direct gradient analysis indicated that SO₄^2- and pH (P < 0.05) were significantly correlated with the community composition of SRB. These findings offer valuable insights into the temporal trajectory of SRB communities in different hydraulic fracturing habitats and have important implications for understanding the enrichment of microorganisms that may pose a potential corrosion threat to gas well infrastructure during this process.