Experimental research on methane displacement in coalbed by carbon dioxide under thermo-mechanical action

In order to study the methane displacement in coalbed by carbon dioxide with different volume stress and temperature,using self-developed seepage device for triaxial absorbing and desorbing,an experimental study was car- ried out on methane displacement with the consideration of volume stress and temperature variation under the thermo- mechanical action,and under the pore pressure of equaling to coalbed. The results show that at the same temperature, the adsorption decreases with the increase of volume stress,and the gradient declines obviously;the volume stress and temperature are the main causes of methane displacement,and the formula is fitted that the coalbed methane displace- ment varies with volume stress change at 20-50 ℃ . At the same temperature,the displacement efficiency drops linear- ly with the increase of volume stress;as temperature increases,the displacement efficiency increases obviously. At the same temperature, the replacement volume ratio expands; with temperature increase, the replacement volume ratio falls,and the gradient remains the same.