Simulation for H2S Toxic Area Classification in Gas Industry with ALOHA and LOPA
Hydrogen Sulfide (H2S) is one of unwanted and toxic component in Sour Oil and Gas reservoir. In Chemical and Oil & Gas industries, one of risk analysis method for flammable and toxic gas leak is through Consequence Modelling and Classification of Areas based on risk/hazard level. Areas where equipment containing hazardous material are classified based on the probability of releases from each equipment. Similar method is being proposed for H2S toxic gas releases hazard specific for Indonesia Offshore Gas Facilities. This classification is intended to analyze facility siting of Gas platforms and help develop emergency response plan on H2S release scenario. The paper aims to propose a method to do an area classification of H2S risk through dispersion simulation with ALOHA (Areal Locations of Hazardous Atmospheres) and LOPA (Layers of Protection Analysis). The leak size can be selected based on the frequency leak of 1.410-4/year through lookup table of industry failure database. The safe distance is determined based on correlation obtained by simulation dispersion at varied H2S mass release rate. Based on the proposed method, the area classification can be conducted with a semi-qualitative method by combining dispersion simulation and probability analysis using LOPA.
Keywords: area classification, gas dispersion, H2S