Probability of receptor lethality in blowout of sour gas wells

Abstract

By the Fluent software on the high-performance cluster system of parallel computing, the computational fluid dynamics method was applied to simulate the temporal and spatial evolvement of hydrogen sulfide's concentration during the blowout of a typical natural gas well with hydrogen sulfide in Sichuan and Chongqing. The difference and integral calculations were conducted to obtain the distribution of toxicity load for hydrogen sulfide. Then, the probability of lethality for receptors around the well was analyzed. The topographic condition of the gas well had a great impact on the calculation results. The topographic condition of the selected gas well was flat on the east, west, and north sides, dominantly low mounds, and there was a mountain of 1230 m altitude on the south side. Because of the influence of the mountain, the position of second peak value for toxicity load and lethality probability can reach 1000 m from the well under northerly wind. So it must be fully considered when performing the consequence simulation and quantitative risk assessment of gas wells. This method is preferable in the quantitative risk assessment and safety planning of sour gas wells. Key words: sour gas well, blowout, receptor lethal probability, quantitative risk assessment, topographic condition