This paper discusses the study of storage corrosion of coiled tubing (CT) and the development of inhibitors to counteract these effects. This study was undertaken to circumvent corrosion of coiled tubing after being stored for extended intervals. The primary modes of corrosion attack during storage are non-localized (uniform), pitting and crevice corrosion. Each mode and its impact to coiled tubing services is discussed. Experiments were performed in the laboratory on a number of commercially available inhibitors to determine the best candidate for both internal and external protection of the tubing. Saltwater immersion, salt-spray, and electrochemical tests were used to evaluate each inhibitor. The system chosen was a water-based inhibitor for internal protection and a separate, paraffin-based inhibitor for external protection. Results of laboratory experiments compared with field application experiences for each inhibitor are discussed.
Keywords: atmospheric corrosion, inhibitor, accelerated testing, coiled tubing.