多场耦合下煤岩渗透率演化规律——以平煤十矿为例

Evolution of coal rock permeability with multiphysics coupling——taking Ping Mei No.10 mine as an example

为深入探讨多场耦合下的煤岩渗透率演化规律,文中以平煤十矿己15-16煤为研究对象,进行了不同围压、气体压力和温度条件下的型煤渗透率测定实验研究。结果表明:围压决定煤岩内部的有效应力,围压增加促使煤体被压缩,渗流和扩散通道变窄,导致煤岩渗透率降低;气体压力升高促使煤体对气体的吸附量增加,导致吸附于孔裂隙壁的气体分子增加,进而降低了孔裂隙截面积,同时煤基质吸附大量气体产生膨胀变形,从而导致煤岩渗透率的降低;温度的升高引起气体分子渗透和扩散能力的改变,同时也导致煤基质的膨胀变形,两者耦合作用促使煤岩渗透率随温度升高先增加后降低,即在20~40℃时,温度升高促使煤岩渗透率增加,而40~100℃时,温度升高促使煤岩渗透率整体上逐渐降低,但在围压较低时煤岩渗透率具有一定的波动。

In order to further explore the evolution law of permeability of coal rock with multiphysics coupling,coal permeability experiment under different confining pressure,gas pressure and temperature was carried out in this paper.Experimental results show:Firstly,the confining pressure controls the effective stress inside the coal rock,so the increase of confining pressure causes the coal to be compressed,then the seepage and diffusion channels become narrower,resulting in a decrease in the permeability of the coal rock.The increase in gas pressure causes increasing amount of gas adsorbed in coal.A large number of gas molecules adsorbed on the pore surface reduces the cross-sectional area of the pores.At the same time,the coal matrix adsorbs a large amount of gas to cause expansion deformation,resulting that the permeability of coal is reduced.The increase in temperature causes a change in the permeability of gas molecules and the expansion of the coal matrix.The coupling of the two causes the coal rock permeability to increase first and then decrease with increasing temperature,that is,at 20 to 40℃,the increase in temperature promotes the permeability of the coal to increase,whereas at 40 to 100℃,the increase in temperature causes the permeability of the coal to decrease as a whole,while the permeability of coal has a certain fluctuation at a low confining pressure.