Global Benefits and Operational Challenges of Vessel Relocation

Movement of moored floating production vessels, such as Spars, Semi-submersibles, Deep Draft Floaters and Floating Production Units, due to environmental loading is often considered a design challenge to be addressed during the design phase of a structure. Proactive vessel relocation through mooring line adjustment can be integrated as part of an operational method to improve and extend component lives. This method may be implemented during the initially planned life of the structure to overcome riser fatigue life challenges, or as one of the methods to extend service life. The benefits are particularly noteworthy for steel catenary risers and mooring systems and have been discussed in previous works. However, vessels often deviate from the original relocation plan in practice. This paper assesses the benefits of a vessel relocation program with conscientious focus on the associated operational challenges. Risks associated with vessel relocation are also investigated. Suggestions are made to optimize such a program and to minimize interruption to production.