CLASS APPROACH FOR LIFE EXTENSION PROCESS OF FLOATING PRODUCTION INSTALLATIONS

摘要

In the last five years, during the crest of the offshore industry boom, classification societies have received frequent queries on the feasibility of service life extension for different floating production installations (FPIs). Class society ABS initiated research into its records regarding the status of the oil and gas production fleet, and the sound engineering procedures used to cover demand in specific regions. Results indicate that proper life extension assessments would be required for different FPI types, including column stabilized units (CSUs), spars, tension leg platforms (TLPs), and FPSOs, by region. In the recent down cycle of the Offshore Industry, life extension of FPIs becomes a more cost-effective solution than decommissioning, for production boosting and stariup of new fields. Industry need to extend service life according to up-to-date environmental data and enhanced Classification Rules requires verification that the FPIs to be structurally adequate, and to withstand new design operational loads and additional equipment. ABS has published life extension guidance notes to provide procedures for life extension of aging FPIs. The approach provided in the Guidance Notes is to evaluate the condition of the asset, to verify its adequacy for the extended service based not only on the prescriptive Rule Requirements but also on analysis of unit's operational behavior at past and present condition, and on comparison with the future predicted behavior for late life. With these verification results, the owner and ABS are able to account for risk and their mitigations and to take appropriate actions to achieve the life extension. The process starts with a baseline survey and a review of the design and in service engineering and survey documentation to establish the current condition, evaluate the asset in "as-is" condition, reassess the strength and remaining fatigue life, implement mitigation and repairs and customize in-service inspection programs or risk-based inspection programs for the extended service. The approach developed was segmented in phases to include decision points to allow owners and operators to interact with Class during the engineering and survey processes on technical issues. These include structural degradation during operation, previous repairs and the most current condition. Particularly, this approach will allow owners/operators to have the chance to make their decisions at certain stages throughout the process and not just at the end of detailed assessments. This paper will summarize the procedure for life extension provided by the guidance notes, and provide an introduction of ABS software HM3D which can be utilized during the life extension process.