Case Studies of Microbiological Influenced Corrosion (MIC) in Pipelines

Abstract Microbiologically influenced corrosion (MIC), also known as microbial corrosion, is a type of electrochemical corrosion that can be caused by the activity of microorganisms in oil and gas pipeline. Pipeline corrosion is influenced by a large number of factors such as fluid type, fluid chemistry, temperature, pH, aeration, and microorganisms. MIC is the one closely related to the activity of living microorganisms which includes microalgae, bacteria, archaea, and fungi. MIC, in any form, starts with the formation of a biofilm on the metal substrate and produces metabolic products which causes corrosion. Microbial corrosion of steel is divided into aerobic and anaerobic corrosion mechanisms. Anaerobic microorganisms grow and control corrosion, in the absence of oxygen. When it comes to biocorrosion of steels, iron-reducing bacteria (IRB), iron- and manganese-oxidizing bacteria, acid-producing bacteria, sulfur-oxidizing bacteria (SOB), and sulfate-reducing bacteria (SRB) and methanogens are microorganisms which are recognized to have more detrimental effects on corrosion resistance. MIC corrosion of pipeline steel due to the IOB, IRB, SOB and SRB was observed when evaluated for bacteria using Quantitative polymerase chain reaction (qPCR) DNA extraction method. This paper presents few such case studies along with metallurgical failure analysis in which SRB, SOB and IRB were the primary MIC contributors.