Abstract
Aging offshore hydrocarbon gathering and transmission pipeline systems present a number of unique challenges to identification of the predominant internal corrosion mechanism(s) and the selection of effective mitigation measures, particularly since biotic and abiotic corrosion threats often exist concurrently. Integration of data from design and construction, pipeline operations, fluid composition analysis, maintenance pig returns, and inspection, along with internal surface condition information provided by extended coupon analysis, is often used to develop a basis for selection of effective mitigation. The relationship between the chemical composition, microbiology and physical nature of surface deposits with the corrosion initiation morphology and severity observed on a coupon provides important clues to the mechanisms driving localized corrosion. This understanding resulted in the development of optimal corrosion inhibitor formulations for use in an offshore gathering system. In this paper the systematic use of extended analysis coupons for corrosion mitigation selection is illustrated through detailed case studies.
