Microbial corrosion in oil transportation and storage systems: laboratory-scale study on biofilm and pitting formation

Microbiologically influenced corrosion (MIC) is critical in oil transportation systems, where biofilm formation accelerates metal deterioration, often leading to structural failures and economic losses. Several microbial groups contribute to MIC by interacting with the metal surface or by producing corrosive metabolites that facilitate localized metal loss. In this study, the microbial communities of pigging scrapings and water produced from crude oil and naphtha storage tanks in several oilfields in Colombia were characterized using next-generation sequencing technologies. Additionally, laboratory simulations evaluated MIC and biofilm formation under dynamic and static conditions using native microbial strains. Carbon steel coupons (AISI/SAE 1018) were installed in custom-designed bioreactors, a side-stream system, and exposure setups developed by the Corporación para la Investigación de la Corrosión (CIC). Exposure times ranged from 6 hours to 120 days. Sessile bacterial counts were performed with liquid culture media, complemented by microscopy (SEM) for biofilm characterization and pitting depth determination. Biofilm formation was detected within 12 hours, while sessile SRB colonization occurred at 6 hours. After 90 days, the localized MIC pitting reached 35.5 µm, with a maximum corrosion rate of 5.5 mpy, classified as moderate according to the standard AMPP SP 0775-2023. These findings highlight rapid biofilm development and its correlation with MIC severity under both dynamic and static conditions. The present analysis confirms that the microbial composition associated with production has significant corrosive potential. The presence of these microorganisms and the pitting depths observed indicate a clear MIC threat in such systems. Implementing routine microbiological monitoring, optimizing maintenance schedules, and strengthening internal pipeline cleaning procedures are recommended to the reduce threat of MIC. In the case that MIC materializes in field-installed biocoupons and coupons, biocide treatments should be considered to prevent further structural degradation of oil transportation and storage systems.