Assessment of safety barriers for the prevention of cascading events in oil and gas offshore installations operating in harsh environment

Fire in the topside production area of offshore Oil and Gas (O&G) platforms has the potential to trigger cascading events and may lead to catastrophic consequences for operators, environment and asset. Safety barriers, such as hardware systems and emergency response, are critical elements aimed at preventing the propagation of this type of scenarios. Harsh environmental conditions may strongly affect the integrity of protective equipment and significantly hinder an effective and timely emergency response, with a consequent increase in the risk level. The present study is aimed at developing a structured methodology to the quantitative performance assessment of safety barriers, specifically addressing the analysis of offshore facilities operating in harsh and sensitive environment. An expert judgment elicitation procedure is adopted to score external factors associated with harsh environmental conditions. Simplified relationships are established for availability and effectiveness evaluation of safety barriers in offshore O&G platforms. A dedicated framework is developed for the analysis of emergency response. The approach is tested through the application to a case study, aimed at the assessment of the influence of harsh environmental conditions on the risk due to cascading events in a reference offshore installation.