Deluge and gas explosion risk management: A decision support framework

Abstract: On offshore installations for oil- and gas exploration, fire-water deluge systems are often installed to mitigate the effect in case of fires. Recent research has shown that the deluge can also be used to mitigate explosion consequences by activating deluge on gas detection. The effect of deluge on the explosion risk is however very complex and could in some cases lead to increased explosion risk instead of risk reduction. This thesis puts the problem of explosion risk management and deluge into a decision making context and investigates different aspects of relevance to the decision on if deluge should be used as explosion risk reduction measure or not. A framework has been derived on how to produce a decision support which reflects both the decision makers preferences and the scientific sound methods of calculating the explosion risk with and with-out deluge. The four most important features of the framework include a course decision analysis, the use of computational fluid dynamics to quantify the consequences, Monte Carlo analysis and the application of the NORSOK Z-013 standard. The framework also includes a cost- benefit analysis model and a model to estimate the time from start of leakage to efficiently activated deluge. The framework was then tested practically by applying it in a case study of an installation in the North Sea. During this exercise, problems and opportunities of improving the framework became obvious. Based on this hindsight knowledge, the framework was improved. A recommendation for the case study object is also presented.