Through the experimental data of hydrocarbon generation simulation and analysis on biogenetic gas reservoir,on the basis of summary of forming process of biogenetic gas as well as the evolution features of organic matter of biogenetic gas source rocks,the generation and evolution mode of biogenetic gas is established to provide the criteria for gas generation capacity of biogenetic gas source rock. Under the effect of microbes,organic matter can generate biogenetic gas through CO2 reduction and fermentation...