A dynamic approach to identify hazardous areas for H2S-containing natural gas release and explosion accidents on offshore platforms

Many efforts have been made to predict and mitigate the toxic impact and explosion impact. However, they are inadequate for the chain accident of toxic gas-containing flammable gas release and explosion since these two hazardous impacts can happen continuously. Accordingly, an integrated approach concerning chain accident consequence assessment is proposed, in which the human behavior is taken into account. The risk-based concept and grid-based concept are introduced in this approach to integrate the adverse impacts. The approach is applied to a hypothetical chain accident involving H2S-containing natural gas release and explosion on an offshore platform. The emergency evacuation is considered by establishing an emergency evacuation time model. A cumulative H2S inhalation dose along each evacuation trajectory is derived to evaluate the toxic impact by considering the temporal-spatial variation of both H2S profile and sufferers’ positions. The maximum explosion overpressures in the real-time position of the sufferers are extracted to predict the explosion impact. The proposed approach is systematic and efficient for practical engineering applications. It can help to develop safety measures and improve the contingency plan.