中文摘要：

The types of substances in coal rock used bymicrobes, the specific ways in which microbes produce sec-ondary biogenic gas （SBG） and whether substances exist inthe coal seam for the formation of a large amount of SBG areimportant basic scientific issues. This paper conducts a sys-tematic and comprehensive research study on the above issuesusing methods such as the isotopic tracing of gas, the analysisof coal organic geochemistry, and gas-producing simulationexperiments of coal. Results show that the formation of SBG isby the microbial reduction of CO2 and the SBG-producingcoal seam undergoes microbial degradation. The thermogenicheavy gaseous hydrocarbons have also been degraded bymicroorganisms and possibly transformed into microbial-originated CO2. A large amount of CO2, a relatively largeamount of H2 and a certain amount of heavy gaseous hydro-carbons may form in the thermal evolution of coal. Thesesubstances and the microbial-originated COz and coal seamwater can finally become parent materials of SBG. Thesecomponents are rich in coal seams of medium-low thermalevolution, which should be the main coal seams for SBGformation and exploration.

英文摘要：

The types of substances in coal rock used bymicrobes, the specific ways in which microbes produce sec-ondary biogenic gas （SBG） and whether substances exist inthe coal seam for the formation of a large amount of SBG areimportant basic scientific issues. This paper conducts a sys-tematic and comprehensive research study on the above issuesusing methods such as the isotopic tracing of gas, the analysisof coal organic geochemistry, and gas-producing simulationexperiments of coal. Results show that the formation of SBG isby the microbial reduction of CO2 and the SBG-producingcoal seam undergoes microbial degradation. The thermogenicheavy gaseous hydrocarbons have also been degraded bymicroorganisms and possibly transformed into microbial-originated CO2. A large amount of CO2, a relatively largeamount of H2 and a certain amount of heavy gaseous hydro-carbons may form in the thermal evolution of coal. Thesesubstances and the microbial-originated COz and coal seamwater can finally become parent materials of SBG. Thesecomponents are rich in coal seams of medium-low thermalevolution, which should be the main coal seams for SBGformation and exploration.