Test on Carbon Dioxide Permeability in Coal Seam

With the triaxial servo-controlled seepage equipment for thermo-fluid-solid coupling of gas-containing coal, permeability tests of carbon dioxide in the coal seam under the conditions of different pressures were conducted and the sensitivity of the coal-rock permeability to the stress change response was discussed. The research results showed that the infiltration rate of carbon dioxide increased with the increase of the pore pressure under the conditions of same confining pressure and different axial pressure; the larger the confining pressure, the smaller the permeability of carbon dioxide; under the conditions of same confining pressure and different axial pressure, the permeability of carbon dioxide decreased with the increase of the axial pressure. When the pore pressure became larger, the sensitivity coefficient of the stress increased negatively, the senitivity of coal sample to the stress was better. Under the conditions of different axial pressure and confining pressure, the sensitivity coefficiet of the stress gradually decreased with the increase of stress, the higher the stress, the worse the sensitivity of coal sample permeability to the stress.