含硫气井井喷事故受体致死概率分析

Probability of receptor lethality in blowout of sour gas wells

采用计算流体力学的方法,在基于并行计算的高性能集群系统平台上采用计算流体力学软件Fluent对川渝地区某含硫气井井喷事故状态下硫化氢气体的扩散动力学演化过程及影响范围进行数值模拟研究,并通过差分和积分计算获取了硫化氢毒性负荷的分布场,进而分析了气井周边区域的受体致死概率。结果表明,含硫气井所处的地形条件对硫化氢浓度场及受体致死概率计算结果影响很大:所选计算井其东、西、北三面地形平坦,以浅丘为主,南侧背靠海拔1 230 m的山峰,受井口南侧山峰的影响,北风下井口附近区域毒性负荷及受体致死概率最高,次高峰值处距井口约1 000 m,因此在对气井进行事故后果模拟及定量风险分析时必须充分考虑地形的影响。本方法可用于含硫气井的定量风险评价及安全规划的制定。

By the Fluent software on the high-performance cluster system of parallel computing, the computational fluid dynamics （CFD） 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, and 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 1 230 m altitude on the south side. Due to the influence of the mountain, the position of second peak value for toxicity load and lethality probability can reach 1 000 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.