Experimental Study on Seepage Rule of Gas under the Condition of Non Isothermal

摘要

Through the experiment of seepage flux of coal sample gas measuring under different temperature, the affecting factors of seepage flux are studied, seepage rule of coal sample gas is obtained concerning temperature condition, the basis of coal seam gas mining of injection of heat and rising temperature is provided. Based on the existing experimental devices of coal sample under the condition of three-dimensional stresses, the temperature controlling system is added, the seepage flux is measured under different combining conditions of temperature, confining pressure and axial pressure, pore pressure. Under the same conditions of confining pressure and axial pressure, and pore pressure, seepage flux of coal gas decrease as the temperature increasing when in the isothermal desorption; seepage flux of coal gas increased significantly than sorption and desorption at 20°C when in the calefactive desorption, the sorption at 20°C and desorption at temperature increased to 40°C. In the calefactive and isothermal conditions, seepage flux shows nonlinear incremental relationship along with pore pressure increasing. After coal sample heated, heated expansion of solid coal and endothermal expansion of gas are two important factors of affecting seepage flux of gas; in the process of mining coal seam gas, intermittent injection of heat mining is more propitious than continuous injection of heat mining to outputs of coal seam gas.