Pool-Forming Stages and Enrichment Models of Medium-to High-Rank Coalbed Methane

The pool‐forming mechanism of coalbed methane has its own characteristics. In this paper, based on studies on the typical coal‐bearing basins in China, it is pointed out that the reservoir formation of medium‐ to high‐rank coalbed methane has experienced three critical stages: the coalbed methane generation and adsorption stage, the coalbed adsorption capacity enhancement stage, and the coalbed methane desorption‐diffusion and preservation stage. The regional tectonic evolution, hydrodynamic conditions and sealing conditions play important roles in the stage of coalbed methane desorption‐diffusion and preservation. Medium‐ to high‐rank coalbed methane has three types of enrichment models, that is, the most favorable, the relatively favorable, and the unfavorable enrichment models.