Temporal changes of bacterial and archaeal community structure and their corrosion mechanisms in flowback and produced water from shale gas well

Abstract

Superficial research on flowback and produced (FP) water from shale gas wells limit the targeted practice of corrosion protection and wastewater treatment. This study analyzes the injected fluid and the FP water at different stages in a single shale gas well with freshwater hydraulic fracturing (HF) in the Changning Shale Gas Field located in the Sichuan Basin, China. The analysis includes water-quality parameters, corrosion electrochemical properties, as well as bacterial and archaeal community structure. The results show that changes occurred at different exploration stages to the main corrosion microorganisms in the FP water, including bacteria and archaea, and their corrosion mechanisms. In the flowback stage, the genera Pseudomonas, Caenispirillum, Proteiniphilum, and Methanothermobacter were the main corrosive microbiota, whereas sulfur-cycling bacteria such as Arcobacter, Marinobacterium, and Desulfuromonas played the main corrosive role during the production period. After two months of production, the genus Arcobacter was highly enriched in the produced water, which is an atypical sulfate-reducing bacteria genus, and the corrosion rate reached 0.2518 mm/a as determined by corrosion electrochemistry. This study characterized the corrosivity of FP water intuitively using electrochemical tests and broadened the horizons of the corrosion mechanism caused by microbial succession over the shale gas exploitation and production stages. It may provide novel guidance for the treatment of FP water for recycling and corrosion protection in shale gas production.