Re-commissioning of Mothballed Pipelines Offshore California: A Success Story of Cleaning, Pigging, Monitoring and Integrity Management

Abstract Three unused intra-field pipelines exist between two platforms in a producing complex located offshore California. The complex produced 2,200 BOE/d and the project was to bring an offline platform online in order to boost production. The platform had not produced since 1999 and the pipelines had not seen active duty since that time. The major challenge for this project was the condition of the intra-field pipelines and the requirement to provide the US Minerals Management Service (MMS) with a robust integrity management strategy in this environmentally sensitive area of the Pacific Ocean. This paper gives details on the external pipeline condition as determined by ROV coupled with cathodic potential measurements. Further details are given on how the pipelines were intelligently pigged including the chemical cleaning procedure that enhanced the efficacy of the pigging runs. The well start-up strategy and a description of the operating conditions of the facilities and pipelines are given. The corrosion mitigation and monitoring strategy form the bulk of discussions. Details are also given on the initial batch treatments to establish a protective chemisorbed film on the pipelines as well as the subsequent maintenance of these films. The discussion of the monitoring strategy includes direct electrochemical monitoring using ER probes in addition to indirect monitoring using amine residuals, iron and manganese counts and corrosion coupons. Final details are given on the successful start up of the platform and pipelines and the success of the integrity management strategy. The proactive work gave MMS assurance on the continued integrity of the pipeline, protection of production, and of the environment.