Assessment of availability for a phased-mission system having multiple operational modes with Monte Carlo method: a case study for offshore drilling system

Abstract

This study suggests a new approach, based on Monte Carlo simulation (MCS), to estimate the availability of a phased-mission system that accompanies both transitions within an operational mode caused by component failures and transitions between operational modes due to external factors. The whole operation is composed of the normal and abnormal operation states, which have system configurations that differ from each other and that consist of several sequential operational modes with distinct time durations. The failure of components may occur randomly at any time during the normal operation state, and the unscheduled transition to the abnormal operation state and further transition to a critical event may result in catastrophic accidents. To address the limitations of conventional Monte Carlo techniques in the availability assessment of the phased-mission system, a revised MCS is used that considers the different types of transitions that can be triggered by component failures and externally induced factors. The suggested approach is capable of providing not only the realistic lifetime scenario but also information on the precise system availability. The validity of the approach is demonstrated by applying it to estimation of the availability of an offshore drilling system with actual operational data.