The Analysis of Geochemical Characteristics and Origins of CBM in 9^# Coal Section of Sijiazhuang Mine in Yangquan Mining Area

In order to increase the production of coalbed methane in the Shijiazhuang Mine, the desorption of CBM and geochemical characteristics were analyzed. The analysis results of field desorption and gas component of coal show that in the complete desorption process of coal in the 9^# coal section, the volume fraction of methane first increases and then decreases, the volume fraction of nitrogen first decreases and then increases, the volume fraction of heavy hydrocarbon is consistent with the change trend of methane, but not synchronously, but later. The analysis of carbon isotope shows that the coal seam δ¹³C(CH₄) shows an increasing trend as a whole with the deportion, δ¹³C(CH₄) grows as it moves away from coal seam. The formation of CBM in the 9^# coal section is mainly thermal, it has undergone diffusion and migration in the later stage, so the biological effects are not obvious.