Based on the occurrence status of coalbed methane and structure setting of coal beds

the accumulation models of coalbed methane are divided into three types:self-source and self-reservoir adsorbed gas

self-source and self-reservoir free gas

and inside-source outside-reservoir gas.Coalbed methane enrichment and production mechanisms vary with various accumulation models.According to methane content and δ

13

C

1

distribution in different coalbed methane accumulation in Qinshui Basin

eastern margin of Ordos Basin

Fuxin Basin and Tiefa Basin

three coalbed methane accumulation stages are indicated as early accumulation stage

late structural-reworking accumulation stage and secondary accumulation stage during production.The secondary accumulation is induced by inter-zone and inner-zone flow during production.Micro-cycles within thick coal beds are analyzed based on sedimentary facies and the coal bed intervals with high coalbed methane content are identified.Furthermore

the types of coal-forming parent materials and their control on coalbed methane enrichment and productivity are studied based on analysis of sedimentary facies.This paper also discusses tectonic stress field and hydrodynamic force influencing coalbed methane accumulation.Finally

this paper summarizes the production characteristics of coalbed methane.The production of methane well can be divided into three stages including blocked

unblocked

and unsaturated stages.The unsaturated stage is subdivided into several step-like declining stages.Structural positions and inner-layer heterogeneity result in three types of self-supporting

exporting and importing production characteristics.