LAUSR

For nearly 20 years, CO2 has been injected into coal seams to enhance the recovery of methane in a process known as enhanced coal bed methane (ECBM). However, there is a huge complexity associated with this process, mainly due to the generating complex coal chemicophysical structure rearrangement. This review paper aims to comprehensively discuss two main influencing factors upon CO2 injection in deep coal seams: (1) mobilization of hydrocarbon and (2) coal matrix swelling. CO2 injection into deep coal seams may remove available polycyclic aromatic hydrocarbons (PAHs) from the coal matrix and mobilize them in the coal seam. The amount of hydrocarbon that is mobilized from the coal matrix by the injected CO2 is dependent on coal rank, maceral content, type of available hydrocarbons in the coal mass (both dissolving and nondissolving types), and phase state of the injected CO2 in the seam. Supercritical CO2 has greater solvent ability and, therefore, has the ability to extract a greater percentage of hydroc...