ABSTRACT
This paper introduces a method of performing a semi-quantitative risk assessment of subsea production systems in the concept selection phase of the asset. The objective of the analysis is to support the decision of the involved parties for selecting the concept to be developed for producing and transferring the hydrocarbon. Accordingly, a review of the different failure modes, the underlying failure causes and their relevant reliability and Risk Influencing Factors (RIFs) are introduced, in order to give an extended explanation of failure of subsea equipment. Afterwards, the impact of the relevant RIFs is reflected on the different failure causes for the sake of producing more specific quantified failure rates of subsea systems. Quantified failure rates are then used as the start point of the Event Tree Analysis (ETA) in order to model the development of the possible accidental scenarios. Besides, the end terminals of the ETA are linked with different linguistic consequence groups, where each of these groups denotes a quantified magnitude of consequences to human, environment and assets. However, the above method of semi-quantitative risk assessment is implemented on a case study from offshore Brazil for the practical demonstration.
