Coalbed gas in the Dafosi mine field in China comes from a mix of biogenic and thermogenic sources. The gas is mostly methane and has dry gas characteristics. The carbon isotopic composition varies depending on the gas origin, with biogenic gas having lower values. The distribution of different gas types is influenced by the fold types in the area. Biogenic gas is found in the southern parts of certain structures, while mixed gas is present in other areas sealed with specific rock types and hydrocarbon concentrations.