Experimental study on desorption and seepage rules of coal-bed gas considering temperature conditions

Through the experiments on permeability and seepage flux of coal-bed gas under different temperatures, the affecting factors of permeability and seepage flux of coal-bed gas were studied, and the rules of permeability and seepage of coal-bed gas were obtained concerning temperature conditions. Using the 3D experimental devices of CBM desorption, the temperature controlling system was added, and the permeability and seepage flux of coal samples were measured under different temperature, confining pressure, axial pressure and pore pressure. It was shown that under the same conditions of confining pressure, axial pressure and pore pressure, the permeability of coal gas decreased as the temperature increased; the permeability increased exponentially as the pore pressure increased under different temperatures. Under the same confining pressure, axial pressure and pore pressure, the seepage flux of coal-bed gas decreased as the temperature increased in the isothermal desorption; in the calefactive desorption, the sorption occurred at 20C and desorption occurred when temperature increased to 40C, the seepage flux increased more obviously than in the sorption and desorption at 20C. Under the calefactive and isothermal conditions, the seepage flux increased nonlinearly as the pore pressure increased. This rule was significant for choosing the way of gas injection heat mining of coal-bed.