挥发性有机含硫化合物在有机质熟化中的演化特征及应用

沉积盆地内天然气形成途径具有多元性，然而其分子组成却相对单一，因此准确拟定天然气成因机理是石油地球化学领域诸多难题之一。气体分子和单体化合物碳-氢同位素组成是目前判定天然气成因机理的常用指标，这些常规指标在实际使用过程中仍有相当局限性。天然气中挥发性有机含硫化合物蕴含了丰富地质-地球化学信息，可能成为判识天然气成因机理的潜在指标，然而相关研究异常薄弱。本项目基于实验室内限定条件下的热-压模拟实验结果，紧扣挥发性有机含硫化合物形成主要途径，着力刻画干酪根初次裂解、原油二次裂解和TSR过程中不同类型挥发性有机含硫化合物的生成消耗阶段和主要控制因素，同时结合室内挥发性有机含硫化合物二次运移物理模拟实验结果，尝试构建表征不同作用过程的分子地球化学指标，并将之应用于我国江汉盆地和四川盆地，希望进一步理清研究区天然气成因机理，明确相关分子指标的可靠性和适用范围。

Several pathways have been identified for natural gas generation in the subsurface within sedimentary basins. However, simple molecular composition of natural gas results in a big challenge in determining the generation mechanisms within the field of petroleum geochemistry. Molecular and stable carbon and hydrogen isotopic compositions of individual compounds are normally employed to evaluate the specific formation pathways, further demonstrating the limitations of these geochemical indicators under natural circumstances. Volatile organic sulfur compounds (VOSCs) are believed to be a potential robust proxy of implying the gas origins by providing the relevant distinct clues. However, little is known about their capability in this aspect. This study focuses on the generation and decomposition of VOSCs as well as the relevant controlling factors of their concentrations during the processes of kerogen primary cracking, oil secondary cracking and thermochemical sulfate reduction (TSR). Based on the experimental results of artificial pyrolysis and petroleum secondary migration, geochemical indicators of VOSCs will be constructed to characterize the specific processes and then applied to clarify the origins of natural gases from the Jianghan and Sichuan basins. This study provides us an opportunity to decipher the formation mechanisms of natural gas in study areas and improves our understanding of the advantages and limitations of these indicators.