Distribution characteristics and controlling factors of δ¹³C₁ value of coalbed methane

The research shows that under the same thermal evolution conditions,the δ¹³C₁ values of CBM is generally lighter than those of coal derived gases,except a few of samples.The variation of methane carbon isotope can attribute to several complicated factors such as the type of source,maturity,effect of desorption diffusion migration,the mixture of secondary methane and the exchange reaction between CO₂ and CH₄.