硫酸盐热化学反应蚀变天然气模拟

Simulation of Natural Gas Altered by Thermochemical Sulfate Reduction

高H_2S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、H_2S、CO_2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,CH_4比例逐渐增大,C_2H_6与C_3H_8含量呈递减趋势。干燥系数与CO_2含量呈明显的正相关关系,干燥系数与H_2S含量以及CO_2与H_2S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。

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, C02 and coke are the main products of such a reaction. With the simulated temperature increasing, the degree of conversion of TSR is inereasing, and the total hydrocarbon content in natural gas is decreasing, showing CH4_gas ratio is gradually increasing, accompanied by the decreasing of contents of CEH6 and C3H5. 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 HaS-bearing natural gas are probably controlled by temperature, carboehain length, metallic ion, water content and H2S concentration in geologic settings.