甲烷和固态硫酸钙的热化学还原反应模拟实验初步研究

碳酸盐岩地层中常伴有硫酸盐岩的沉积，在一定的温度和压力条件下，干酪根热降解生成的气态烃与硫酸盐岩接触后发生热化学还原反应(简称为TSR反应)，使气态烃消失，这可能是造成生气死亡线的主要原因之一。本文对CH4-CaSO4热化学还原反应的热力学问题进行了探讨，发现该反应能够自发进行，而且升高温度对反应有利。利用高温高压模拟装置对CH4-CaSO4反应体系进行了初步的模拟实验研究，通过微库仑、气相色谱和傅里叶变换红外光谱(FT-IR)等分析手段对实验结果进行了进一步验证。结果表明，甲烷和固态硫酸钙能够发生热化学还原反应，生成硫化氢、碳酸钙和水。最后，将CH4-CaSO4反应体系同国内外的研究工作进行了对比，认为本实验研究能够更好地补充和完善TSR反应体系，解释地质条件下工业气藏的死亡线问题。

Simulation experiments on thermochemical sulfate reduction of methane with solid calcium sulfate

The association of sulfate and hydrocarbon is thermodynamically unstable in deep carbonate diagenetic environment. Hence, the redox reactions occur and hydrocarbons disappear inorganically (thermochemical sulfate reduction; TSR). The work on this field has been the subject of much research in recent years. In this paper, the thermodynamic problem between methane and calcium sulfate is discussed to investigate the possibility of this reaction. It is found that the reaction occurs spontaneously and increasing temperature is favored. Thermal simulation experiments on methane and solid calcium sulfate are carried out using autoclave on the conditions of high temperature and high pressure. The properties of the products of the reaction are analyzed by microcoulometry, gas chromatogram and Fourier transform infrared spectrum (FT IR) methods. According to the results, hydrogen sulfide, calcium carbonate and water are the main products during the reaction. Further research on this subject is necessary in future to understand more details of the TSR system and issue of hydrocarbon destruction in gas reservoirs.