Gas dispersion and deflagration above sea from subsea release and its impact on offshore platform

Flammable gas dispersion and deflagration above sea resulting from subsea release have the possibility to cause an adverse impact on the operation safety of surface vessels. This paper presents a systematic simulation of gas dispersion and deflagration above sea from a subsea release using CFD-based approach, aiming to study the evolution process of accident scenario and assess its impact on surface vessels. A jack-up drilling platform is used as a case to discuss the impact of gas dispersion and deflagration. The uniqueness of this study is the integration of release, dispersion, and deflagration scenarios. The simulation includes the modelling of wind flow, gas dispersion and subsequent deflagration due to accidental ignition. The wind flow above sea surface is given using wind speed profile equation to generate steady wind field around offshore platform. Simulation of gas dispersion is conducted based on the generated wind field. The development of flammable gas cloud is predicted, and the dangerous area on offshore platform is assessed. Considering the appearance of ignition source, a deflagration simulation based on dispersion results is performed to predict the consequences including overpressure, high temperature, and heat radiation. Eventually, the damage criterion is utilized to evaluate their impact on offshore platform.