Bacterial community analysis of biofilm on API 5LX carbon steel in an oil reservoir environment

This study aimed to characterize the biofilm microbial community that causes corrosion of API 5LX carbon steel. API 5LX carbon steel coupons were incubated with raw produced water collected from two oil reservoir stations or filter-sterilized produced water. Biofilm 16S rRNA amplicon sequencing revealed that the bacterial community present in the biofilm was dominated by Proteobacteria, includingMarinobacter hydrocarbonoclausticsandMarinobacter alkaliphilus. Electrochemical analysis such as impedance and polarization results indicated that Proteobacteria biofilm accelerated corrosion by similar to twofold (2.1 +/- 0.61 mm/years) or similar to fourfold (similar to 3.7 +/- 0.42 mm/years) when compared to the control treatment (0.95 +/- 0.1 mm/years). Scanning electron and atomic force microscopy revealed the presence of a thick biofilm and pitting corrosion. X-ray diffraction revealed higher amounts of the corrosion products Fe2O3, gamma-FeOOH, and alpha-FeOOH, and confirmed that the microbial biofilm strongly oxidized the iron and contributed to the acceleration of corrosion of carbon metal API 5LX.