Spatial Heterogeneity and Mechanisms of Microbiologically Influenced Corrosion in Shale Gas Gathering Pipeline Accumulated Liquid Environment

In this study, the spatial distribution characteristics and mechanisms of microbiologically influenced corrosion (MIC) in the accumulation liquid environment of shale gas-gathering pipelines were systematically investigated. A simulation device was utilized, and electrochemical tests, gas-liquid analysis, and X-ray diffraction (XRD) were conducted to explore the relationship between biofilm formation and corrosion behavior in different spatial directions. The results indicate that biofilm formation at the 6 o'clock direction occurs earlier, which triggers a high risk of pitting, with an average rate of 0.1922 mm/a. In contrast, biofilm development at the 4 and 8 o'clock directions lags initially, but due to metabolite accumulation, the corrosion rate increases to 0.2608–0.2625 mm/a, with a risk of hydrogen-induced cracking (HIC). Notably, no significant biofilm was observed at 0.5 cm below the liquid level, but H₂S and CH₄ produced by microbial metabolism contributed to the risk of HIC, with a late-stage corrosion rate of 0.3443 mm/a.