Safe and Efficient Disconnection and Towing of the Fluminense FPSO

Abstract This paper discusses the project of disconnecting the Fluminense FPSO's mooring lines to enable the platform's tow to its recycling yard in Denmark. The Fluminense FPSO was moored by a system of nine anchoring lines spread into three clusters, all connected to the platform's swivel turret, allowing it to turn freely and always face the prevailing weather. Like the risers’ removal, all mooring lines required recovery to the installation vessel rather than abandonment on the seabed to minimize environmental impact. The operation was executed by a fleet of five vessels, with four tasked with keeping the Fluminense in position while the fifth performed the recovery. During the tender phase, the contractor was free to define their preferred methodology and chose to remove the lines starting at the bottom, with two tugs connected at the bow to help remove the load from the mooring line. As the disconnection was followed by towing, three out of the five vessels switched from working as position tugs to towing ones. This approach ensured the safe and efficient disconnection and towing of the FPSO, adhering to environmental standards and operational requirements. Route planning and integrity surveillance were critical components during the tow to ensure the safe arrival of the FPSO at its destination. Detailed route planning accounted for potential hazards and environmental conditions, while continuous integrity surveillance monitored the structural health of the FPSO and towing equipment throughout the journey.