Generation and accumulation characteristics of mixed coalbed methane controlled by tectonic evolution in Liulin CBM field, eastern Ordos Basin, China

•The geological evolution histories of research area were analyzed.•A gas generation model involves both biogenic and thermogenic CBM was modified.•The generation and accumulation process of mixed CBM was quantitatively researched.•Relative content of three types of CBM occurred in present coalbed was investigated.

Tectonic movement controlled the different basins evolutionary histories and affects the enrichment and accumulation of CBM of different genesis. The upliftment and depression are one of the important conditions for the generation of secondary biogenic CBM. The present study confirmed that mixed CBM are enriched in the Taiyuan formation at Liulin CBM field. The experimental results illustrated that the generation and accumulation of CBM in research area can be divided into three evolutionary stages. Diffusion, permeation and cap outburst dissipation were determined to be the main migration mechanisms of mixed-CBM. Secondary biogenic CBM can supplement the dissipation of thermogenic CBM.