Influence of MIC on corrosion of oil field water injection pipelines

Water injection or water flooding is widely used as a secondary recovery method to increase the production of oil usually from mature oil wells. It requires the injection of water into the reservoir, typically using carbon steel pipelines. Their corrosion is a major issue for the oil and gas industry, involving high costs of periodic chemical treatment, including biocides, oxygen scavengers, corrosion and scale inhibitors, and pipeline pigging. There is also the high potential cost of premature failure of the pipelines relative to life-time predictions, and the associated potential for unpredicted costs and major environmental implications should the pipeline fail. The present paper presents a review of a pilot study supported by the oil industry and the European Community that aimed to improve understanding of the corrosion behaviour of these pipelines. It draws on data and observations for the long-term corrosion, water quality, intelligent pigging records and microbiological testing to gain a better understanding why some pipelines suffer mild corrosion yet others, apparently similar, are prone to highly aggressive channelling corrosion. Herein the documented experience of several pipelines is reviewed. Observation data taken into consideration include pigging operation information, composition of corrosion products and their amount, corrosion rates and pipe geometry, identified biological consortia, water chemistry and process parameters. Also, the distribution of corrosion along the pipeline as well as the localization of corrosion attack is noted. Preliminary correlations between and conclusions about observed corrosion, operational conditions and service history are made. A Joint Industry research project currently is being arranged by the offshore oil industry to extend this work.