Abstract:

Using the parent anaerobic methanogen flora enriched from lignites in the Zhaotong basin, Yunnan, a simulation
experiment was carried out in order to analyze the process and possible approach of the biogenic coalbed gas (CBG) generation.
Results showed that the process of the biogenic CBG generation in a period of 130 days underwent at least two gas generation
peaks with the higher gas generation rate at the first peak than that at the secondary peak. Gas produced during the first peak
came mainly from the huminite group and the biodegradation of the inertinite and liptinite groups was strengthened relatively
during the secondary peak. Plots of the carbon isotopic composition to the hydrogen isotopic composition of the simulated methane
indicated a major approach of the acetate fermentation by which the biogenic methane was generated. During the stimulation
process, the methane concentration raised with the drop of the carbon dioxide concentration. Carbon isotopic composition of the
methane tended to become lighter and the hydrogen isotope composition to become heavier in the late period of the simulation
process. These data indicate the carbon dioxide-reduction of the partial methane generated in the late period of the stimulation.