热力作用下煤层注CO_2驱替CH_4试验研究

为研究体积应力和温度对于煤层注CO2条件下CH4驱替量的影响规律,利用自制三轴吸附解吸试验装置,对煤试件开展考虑煤层体积应力和温度热力作用影响的与煤层等孔隙压注CO2驱替CH4试验研究。试验结果表明:相同温度条件下,气体吸附量随体积应力增加逐渐减小,下降梯度明显;体积应力是煤层CH4驱替量的主要影响因素,拟合得出20~50℃区间内煤层CH4驱替量随体积应力变化的计算公式。在相同温度条件下,随着体积应力增加,CH4驱替效率逐渐减小,近似于线性变化规律;随着温度升高,CH4驱替效率上升显著且梯度明显。在相同温度条件下,随着体积应力增加,置换体积比相应增加;随着温度升高,置换体积比减小,近似呈等梯度下降规律。

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 carried 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 displacement varies with volume stress change at 20-50 ℃.At the same temperature,the displacement efficiency drops linearly 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.