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Purpose This paper aims to investigate the anti-biocorrosion performance and mechanism of the Cu-bearing carbon steel in the environment containing sulfate-reducing bacterial (SRB). Design/methodology/approach The biocorrosion behavior of specimens with Cu concentration of 0 Wt.%, 0.1 Wt.%, 0.3 Wt.% and 0.6 Wt.% were investigated by immersion test in SRB solution. By examining the prepared cross-section of the biofilm using focused ion beam microscopy, SRB distribution, bacterial morphology, biofilm structure and composition were determined. The ion selectivity of the biofilm was also obtained by membrane potential measurement. Moreover, the anti-biocorrosion performance of the Cu-bearing carbon steel pipeline was tested in a shale gas field in Chongqing, China. Findings Both the results of the laboratory test and shale gas field test indicate that Cu-bearing carbon steel possesses obvious resistance to microbiologically influenced corrosion (MIC). The SRB, corrosion rate and pitting depth decreased dramatically with Cu concentration in the substrate. The local acidification caused by hydrolyze of ferric ion coming from SRB metabolism and furtherly aggravated by anion selectivity biofilm promoted the pitting corrosion. Anti-biocorrosion of Cu-bearing carbon steel was attributed to the accumulation of Cu compounds in the biofilm and the weaker anion selectivity of the biofilm. This research results provide an approach to the development of economical antibacterial metallic material. Originality/value MIC occurs extensively and has become one of the most frequent reasons for corrosion-induced failure in the oil and gas industry. In this study, Cu-bearing carbon steel was obtained by Cu addition in carbon steel and possessed excellent anti-biocorrosion property both in the laboratory and shale gas field. This study provides an approach to the development of an economical antibacterial carbon steel pipeline to resist MIC.

H2S corrosion behaviors of P110, Fe-Mn-Al, and Fe-Mn-Cr-Ni high-Mn steels were analyzed according to ion-selectivity of corrosion products. At 60 oC and 80 oC, cation-selective troilite restrain diffusion of corrosive ions to the substrate. The corrosion rates were low, and uniform corrosion occurred. At 100 oC and 205 oC, anion-selective pyrrhotite caused accumulation of Cl− between corrosion scale and substrate. Corrosion rates were high and localized corrosion happened. Crystal atom stacking models of iron sulfides were built, and the adsorption energy of ions on the exposed surface was calculated to discuss the ion-selectivity mechanism. The effect of alloy elements on corrosion behavior was analyzed.