| Abstrakt: |
CO 2 injection technology into coal seams to enhance CH 4 recovery (CO 2 -ECBM), therefore presenting the dual benefit of greenhouse gas emission reduction and clean fossil energy development. In order to gaze into the features of CO 2 injection's influence on reservoir pressure and permeability, the Thermal-Hydraulic-Mechanical coupling mechanism of CO 2 injection into the coal seam is considered for investigation. The competitive adsorption, diffusion, and seepage flowing of CO 2 and CH 4 as well as the dynamic evolution of fracture porosity of coal seams are considered. Fluid physical parameters are obtained by the fitting equation using MATLAB to call EOS software Refprop. Based on the Canadian CO 2 -ECBM project CSEMP, the numerical simulation targeting shallow low-rank coal is carried out, and the finite element method is used in the software COMSOL Multiphysics. Firstly, the direct recovery (CBM) and CO 2 -ECBM are compared, and it is confirmed that the injection of CO 2 has a significant improvement effect on methane production. Secondly, the influence of injection pressure and temperature is discussed. Increasing the injection pressure can increase the pressure difference in the reservoir in a short time, so as to improve the CH 4 production and CO 2 storage. However, the increase in gas injection pressure will also lead to the rapid attenuation of near-well reservoir permeability, resulting in the weakening of injection capacity. Also, when the injection temperature increases, the CO 2 concentration is relatively reduced, and the replacement effect on CH 4 is weakened, resulting in a slight decrease in CBM production and CO 2 storage. [ABSTRACT FROM AUTHOR] |
