微生物究竟利用煤岩中的哪些物质并通过何种具体途径形成次生生物气,煤层中是否含有丰富的此类物质可形成大量的次生生物气,是重要的基础科学问题.在多方面研究的基础上,运用气体同位素示踪、煤有机地球化学分析与煤热模拟产气实验等方法,对上述问题进行了系统的综合性研究.结果表明:次生生物气形成的具体途径是微生物还原CO2;产次生生物气的煤层具有遭受过微生物降解的特征;热成因气态重烃亦经历了微生物的改造并有可能形成微生物成因CO2;煤在热演化过程中可形成大量的CO2、较多的H2和一定量的气态重烃,加之微生物成因的CO2及煤层水,都可成为次生生物气的直接母源物质.故可溶有机质与气态重烃等组分都可为其他微生物所利用并最终形成次生生物气的母源先质.中低热演化程度的煤层中这些组分丰富,应是形成和寻找次生生物气的主力煤层. It is an important fundamental scientific issue whether microorganisms make use of which substances in coal rock and through which way to form secondary biogas, and whether the coal seam is rich in such substances to form a large amount of secondary biogas. Based on the results of gas isotope tracing, coal organic geochemical analysis and coal thermal modeling gas production experiment, the above problems were systematically and comprehensively studied.The results show that the specific pathway of secondary biogas formation is microbial reduction CO2. The coal beds producing secondary biogas have been characterized by microbial degradation. The thermal genetic heavy hydrocarbons have also undergone microbial reorganization and possible microbial formation of CO2. Coal can form large amounts of CO2 during thermal evolution. Of H2 and a certain amount of gaseous heavy hydrocarbons, combined with microbial origin of CO2 and coal seam water, can become direct maternal raw materials for secondary biogas, so soluble organic matter and gaseous heavy hydrocarbons can be used by other microorganisms And finally form the parent source of secondary biogas.The enrichment of these components in the coal layers with low and middle temperature evolution should be the main coal for forming and looking for secondary biogas .