As a complex mixture, high-hydrogen-sulfide natural gas has a high risk of poisoning and explosions after leakage. This study combined wind tunnel experiments, computational fluid dynamics (CFD) technology, and risk theory to explore the dispersion characteristics and hazardous area of released mixed natural gas (M-NG) in complex terrain. Based on risk theory, various external safety protection distances under four kinds of risk criteria were predicted. The results indicated that the dispersion process of M-NG in mountainous terrain can be divided into two components: downhill dispersion and cut-slope dispersion. At the same wind speed, the maximum concentrations for different wind directions can differ by a factor of 10. Compared with the results of the wind tunnel tests, the maximum overestimation was 62.9% when simulating the near-field dispersion of M-NG by CFD, while the underestimation was 28.1% for the far-field dispersion. The critical distance was about 1042 m, the dispersion time was 960 s, and the gas concentration was 42 ppm. The wind speed, wind direction, topography, and their interactions have an important impact on the dispersion process and hazard area of M-NG. The study also indicated that in the quantitative risk assessment, more attention should be paid to the toxic hazard of hydrogen sulfide in M-NG rather than the explosion hazard caused by methane. The risk method fully considers the frequency of accidents and the types of protection targets. It can thus be used as a reference for site selection, land use planning, and emergency protection.

高硫化氢天然气作为一种复杂的混合物，泄漏后中毒和爆炸的风险很高。本研究结合风洞实验、计算流体动力学（CFD）技术和风险理论，探索复杂地形中释放的混合天然气（M-NG）的弥散特征和危险区域。基于风险理论，预测了四种风险准则下的各种外部安全保护距离。结果表明，山地M-NG的弥散过程可分为下坡弥散和切坡弥散两部分。在相同的风速下，不同风向的最大浓度可以相差 10 倍。 与风洞试验结果相比，最大高估为 62。通过 CFD 模拟 M-NG 的近场色散时为 9%，而远场色散的低估为 28.1%。临界距离约为1042 m，分散时间为960 s，气体浓度为42 ppm。风速、风向、地形及其相互作用对M-NG的扩散过程和危害区域有重要影响。研究还表明，在定量风险评估中，应更多关注M-NG中硫化氢的毒性危害，而不是甲烷引起的爆炸危害。风险法充分考虑了事故发生的频率和保护目标的类型。因此可以作为选址、土地利用规划和应急保护的参考。临界距离约为1042 m，分散时间为960 s，气体浓度为42 ppm。风速、风向、地形及其相互作用对M-NG的扩散过程和危害区域有重要影响。研究还表明，在定量风险评估中，应更多关注M-NG中硫化氢的毒性危害，而不是甲烷引起的爆炸危害。风险法充分考虑了事故发生的频率和保护目标的类型。因此可以作为选址、土地利用规划和应急保护的参考。临界距离约为1042 m，分散时间为960 s，气体浓度为42 ppm。风速、风向、地形及其相互作用对M-NG的扩散过程和危害区域有重要影响。研究还表明，在定量风险评估中，应更多关注M-NG中硫化氢的毒性危害，而不是甲烷引起的爆炸危害。风险法充分考虑了事故发生的频率和保护目标的类型。因此可以作为选址、土地利用规划和应急保护的参考。及其相互作用对M-NG的扩散过程和危害区域有重要影响。研究还表明，在定量风险评估中，应更多关注M-NG中硫化氢的毒性危害，而不是甲烷引起的爆炸危害。风险法充分考虑了事故发生的频率和保护目标的类型。因此可以作为选址、土地利用规划和应急保护的参考。及其相互作用对M-NG的扩散过程和危害区域有重要影响。研究还表明，在定量风险评估中，应更多关注M-NG中硫化氢的毒性危害，而不是甲烷引起的爆炸危害。风险法充分考虑了事故发生的频率和保护目标的类型。因此可以作为选址、土地利用规划和应急保护的参考。