硫酸盐热化学反应蚀变天然气模拟

高H₂S天然气一般被认为是硫酸盐热化学还原反应(TSR)的结果。在高温高压不饱和水蒸气条件下对天然气与硫酸镁TSR反应进行了热模拟实验研究,确定了TSR反应途径,探讨了TSR可能的地质影响因素。结果表明,天然气与硫酸镁反应主要生成MgO、H₂S、CO₂及焦炭等产物,随着模拟温度升高,TSR转化率逐渐增大,天然气中总烃含量减少,CH₄比例逐渐增大,C₂H₆与C₃H₈ 含量呈递减趋势。干燥系数与CO₂含量呈明显的正相关关系,干燥系数与H₂S含量以及CO₂与H₂S含量之间正相关性低,这可能是由于TSR不同阶段主要控制因素不同导致的。地质条件下,高硫化氢天然气的形成与演变很可能受控于温度、碳链长度、金属离子、水和硫化氢含量这几种主要因素。

Simulation of Natural Gas Altered by Thermochemical Sulfate Reduction

High H₂S-bearing natural gas is usually referred to the thermochemical sulfate reduction (TSR). The thermosimulation experimental study of reaction between natural gas and magnesium sulfate is made in unsaturated water vapor of HTHP. Its possible reaction pathways are determined, and the geochemical characteristics of natural gas in TSR are presented. The possible geologic factors influencing the process of TSR are investigated. The results show that MgO, H₂S, CO₂ and coke are the main products of such a reaction. With the simulated temperature increasing, the degree of conversion of TSR is increasing, and the total hydrocarbon content in natural gas is decreasing, showing CH₄ gas ratio is gradually increasing, accompanied by the decreasing of contents of C₂H₆ and C₃H₈ The apparent positive correlation between the gas dryness and CO₂ content, the low positive correlation between gas dryness and H₂S content, and CO₂ and H₂S content indicate there are different control factors in different stages of TSR. The study shows that the origin and evolution of high H₂S-bearing natural gas are probably controlled by temperature, carbochain length, metallic ion, water content and H₂S concentration in geologic settings.