A practical approach to risk-based gas monitoring system design for oil and gas offshore platforms

The paper discusses the framework of a practical but rigorous approach for designing a risk-based gas monitoring system for offshore oil and gas platforms, able to provide early warnings of gas leakage to anticipate the occurrence or the escalation of hazardous events. The appropriate placement of sensors within a specified platform geometry is a key factor to ensure a proper detection of leakages. The approach, based on modelling and mathematical formulations, aims at optimizing the placement of the sensors in terms of safety assurance and costs, going beyond the common practice of placing the sensors near the potential release points or spatially distributed according to predefined grids. The described work focuses on the process early steps and suggests a method for identifying a sufficient set of representative release scenarios for fluid-dynamic simulations. Their results are then aggregated to highlight the critical points on the platform decks, i.e. those where the gas concentration surpasses the lower flammable limits, either near but also far from the release points. Whenever the number of critical concentration points is too large with respect to constraints such as the maximum allowed number of sensors, optimization methods are used for selecting their best combination and placement. © 2018 International Association for Probablistic Safety Assessment and Management (IAPSAM).