Chemical and Microbially-induced Corrosion in Petroleum Pipelines
The oil and gas industry has a severe problem with chemical corrosion, and microbial contamination of pipelines and infrastructure. The main source of the chemical corrosion is the water that used in digging the crude oil from the ground. It is estimated that the water content in the extracted oil can reach up to 30% in the pipeline. Whilst insufficiently dried oil and gas pipelines have significant general corrosion problems, the industry also has a large need for water pipelines, for example fire/ deluge systems and water injection lines for Enhanced Oil Recovery (EOR). If bacteria are not controlled in these aqueous environments, the consequences for corrosion of the infrastructure is severe and multi parametered. Microbial-initiated corrosion (MIC) is initiated and/or accelerated by the activities of microorganisms, which produce biofilms For example fire water systems are required to be of the “wet riser” style, where the system is full of stagnant water. It is often a challenge to get sufficient biocide around the system to prevent corrosive microbial colonies forming. Most of the corrosion failures of fire systems are due to the microbial corrosion. Similarly water injection lines suffer from corrosion. The usual treatment method is to remove the oxygen to prevent oxygen related corrosion of the steel, but this provides a perfect environment for anaerobes, especially SRBs, which have lead to the souring (production of hydrogen sulfide) of reservoirs. The current approaches to sterilization of lines, such as bleach or oxidizers are incompatible with the aim of reducing corrosion, and many biocides are now prohibited.