Reliability analysis for mooring system of a spar in deepwater Gulf of Mexico

Reliability analysis for the mooring system of a floating production system has been undertaken for sea depths of 1000, 2000, and 3000 m. A methodology has been developed for the estimation of the distribution of extreme values of storm loads on the mooring system during a storm event due to the randomness of the storm event. Probability distribution of sea states in the Gulf of Mexico has been developed in terms of the met-ocean parameters. A relationship between storm severity and storm frequency has been established. A procedure has been developed for obtaining a probabilistic distribution of maximum load with regard to the uncertainty in the sea states in the design life. The uncertainty in the maximum load on the mooring lines due to uncertainty in the input parameters for the response model has been explored. The overall uncertainty in the maximum load on the mooring lines due to different sources has been evaluated. Using these results the component and system reliabilities of the mooring system have been quantified and the redundancy in the system analyzed.