Risk modelling of collision between supply ships and oil- and gas installations

Abstract

This thesis is a framework for risk influence modelling of supply vessel-platform collisions, with the inclusion of central concepts from the Risk OMT model. The framework is a improvement from existing QRA frameworks in the sense that it has taken recent collisions into consideration, and enabled the opportunity to do risk influence modelling for the calculation of site specific risk. It can also be used as a tool for risk management, when the risk influences have been quantified. This model provides no quantifications, but it makes a good foundation for future work.The thesis incorporates knowledge from recent, representative collisions on the Norwegian Continental Shelf (NCS), and considered the guidelines and official safety procedures. This has been used to make three generic collision scenarios are general enough to take all probable collisions into account and at the same time be specific enough to account for the chains of events in previous accidents.These generic collision scenarios has been analysed with event tree analysis (ETA) and fault tree analysis (FTA) to identify and break down the operational barrier functions available to prevent collisions. A large set of risk influencing factors (RIFs) have been identified to be used to express the failure rate probabilities of the basic events found the FTA. These have been included from many different sources, to ensure that all significant RIFs are presented.