Experimental and Analytical Studies on Permeability Reduction of Coal Seam by CO2 Injection

Permeability of coal seam have a strong effect on CO2 Enhanced Coal Bed Methane Recovery(CO2-ECBMR) project. In<br>particular, qualification of permeability reduction due to coal matrix swelling is a key parameter to control CO2 injection<br>and the project sustainability. Swelling experiments using visualization method were conducted. Crushed samples from<br>Indonesia Low Rank Coal (LRC) were used and the experiments were carried out up to 10 MPa at 48° C temperature,<br>resulting CO2 in the supercritical conditions that more appropriate for CO2 injection in the field. Coal swelling which was<br>represent by upward surface movement of column was assumed as total expanded volume for each particle. With this<br>assumption, crushed samples were modeled like block coal samples. For three coal samples, the maximum expanded volume<br>due to the swelling by CO2 adsorption has been evaluated as 0.03 at 10 MPa pressure. Since the swelling results were very<br>comparable to others, this method has more advantage in term of sample preparation and experiment work compare to block<br>coal.