摘要
As a reservoir of coalbed methane（CBM）,the coal seam enables gas to flow and accommodate in it.Different from the conventional sandstone reservoir,the major CBM in the coal seam exists in the adsorbed form and the CBM reservoir is impacted by a lot of factors.Most coalfields in China were formed relatively earlier,experienced many times of tectonics and had complex geological conditions.Thus,the CBM reservoir in China has strong heterogeneity and is difficult to study.This paper summarizes the characteristics of physical property,occurrence state,coal petrology and experimental method of CBM reservoirs.It is suggested that the porosity,permeability,cracks,cleats and micro-cracks can reflect the physical property of CBM reservoir.Temperature,pressure,gas content,hydrodynamic condition,stress state can also reflect the status of CBM reservoir.Coal petrology,coal structure,thickness,macerals composition,metamorphic grade and ash content can impact the characteristics of CBM reservoir.Finally,the main problems and next research orientation in CBM reservoirs are further discussed.
