Case study: successful disconnection of a traditional floating production storage and off-loading unit

Abstract

Decommissioning a producing asset within a low oil-price market scenario with a possibility of resuming production at a later stage is becoming a frequent task. The main objective of the offshore campaign is to release the floating production storage and off-loading unit (FPSO) at the earliest time by disconnecting all production risers, umbilical and mooring chains, and ensuring integrity of the subsea assets for future use. The entire project for the disconnection of this FPSO was managed in four phases. The first two phases were related to shutdown of production and FPSO clean-up. The FPSO readiness for disconnection was required before the final two phases: disconnection of risers and mooring lines. Detailed engineering was carried out in consultation with various stakeholders involved in the project: the regulator, the company, the FPSO owner and the installation contractor. Through feasibility studies, the best option was selected, which included innovative solutions to reduce overall offshore duration and project costs. The project was successfully completed by meeting the key objective of early departure of the FPSO without lost time injury or any significant environmental incidents.