Reliability of Mooring Systems for a Spar

Mooring systems for floating production systems, including the mooring lines and anchors, are currently designed on the basis of individual components. The most heavily loaded line and anchor are checked under extreme loading conditions with the system of lines intact and with one line removed. However, the performance of the floating production system depends more directly on the performance of the system of lines and anchors rather than on the performance of a single line or anchor. The on-going study conducts the reliability analyses using realistic probabilistic descriptions of the extreme met-ocean conditions (hurricanes and loop currents) for the Gulf of Mexico. Presented in this paper is the methodology of calculating the probabilities of failure of a classical Spar during a 20-year design life for individual components.