RAINBOW: An Innovative Approach for Quantitative Risk Assessment of Blowout Events

Abstract

Abstract The uncontrolled eruption of a well introduces safety risks for field operators, potential health injury to people living in proximity of the field and impacts on the environment. The availability of validated predictive tools for quantitative risk assessment of the event is essential not only in design activities or authorization procedures, but also to support the emergency response. Thanks to a decennial collaboration between eni E&P and TEA Sistemi, RAINBOW, an integrated approach for the analysis of a blowout event, has been developed. Through an easy-to-use interface, the user may define fluid characteristics, well geometry, fluid flow-path and environment characteristics to compute the blowout flowrate and to determine the toxic, flammable, heat radiation and oil contamination maps. Alternatively, the release flowrate and characteristics can be computed separately and supplied to the software externally. RAINBOW consists of a Graphic User Interface that puts different models together for simulating separately each phenomenon characterizing a blowout event: multiphase release, spray formation and evaporation, jet development, light or dense gas dispersion, oil rain-out and soil contamination. Some of these models have been specifically developed through R&D activities to fill a gap highlighted by the technical literature. Others are worldwide recognized free software, assessed and selected through experimental and Computational Fluid Dynamics activities. The RAINBOW main structure allows the refined and complex computational tools to be applied without requiring specific skills to the user. Thanks to an in-house module for risk recombination, user may choose to perform simple consequence analysis or complete QRA, in both short and long term approaches. A specifically developed protocol is included in the software for conservative and robust frequency assessment of various well types (onshore, offshore, normal, HTHP) during the different well operational phases, including all credible flow-paths associated with each operation. Risk areas are presented as maps, reporting Local Specific Individual Risk thresholds. Its easiness to use and high running velocity make RAINBOW a suitable support tool for any phases of field development, Risk Management and Emergency Response planning.