不同温度-围压-气体压力下煤体蠕变-渗流演化规律

Creep-seepage evolution of coal under different temperatures,confining pressures,and gas pressures

为实现深部煤层气的高效开采,通过研究不同温度、围压和气体压力下煤体蠕变变形和渗透率演化规律,得到多因素作用下煤体蠕变-渗流耦合关系;采用自行设计的岩石三轴蠕变-渗流装置,对焦煤进行多因素变量下的压缩蠕变-渗流试验。结果表明:温度与煤样的蠕变呈正相关性,随温度的增加焦煤煤样径向和轴向应变变化速率增大且高温(110℃)下这种变化会一直持续直至煤样破裂;围压强度3 MPa与4 MPa的焦煤煤样在温度30、70、110℃下其气体渗透率降低率最大和最小差值分别为7.8%、5.2%、6.5%和4.2%、2.1%、1.9%;焦煤煤样的渗透率最大降低率随着温度水平升高而增大,试验温度110、70、30℃下的焦煤煤样的气体渗透率最大降低率均值依次为91%、84.6%、73.25%。

In order to realize the efficient mining of deep coalbed methane,through studying the creep deformation and permeability evolution laws of coal mass under different temperatures,confining pressures and gas pressures,we obtain the coupling relationship between creep and seepage of coal mass under the action of multiple factors.A self-designed rock triaxial creep and seep device was used to carry out a compressive creep and seepage experiment on coking coal under multi-factor variables.The results show that:temperature is positively correlated with the creep of coal sample:the change rate of radial and axial strain of coking coal sample increases with the increase of temperature,and the change will continue until the coal sample cracks at high temperature(110℃).The maximum and minimum difference of gas permeability reduction rates of coke coal samples with confining pressures of 3 MPa and 4 MPa at temperatures of 30℃,70℃,110℃are 7.8%,5.2%,6.5%and 4.2%,2.1%,1.9%,respectively.The maximum reduction rate of permeability of coking coal sample increases with the increase of temperature.The average maximum reduction rates of permeability of coke coal samples at 110℃,70℃and 30℃are 91%,84.6%and 73.25%,successively.