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为了探讨滑脱效应和基质变形对低渗透煤体渗流特性的影响,以渝阳煤矿8#煤层原煤试件为研究对象,进行4种气体在不同压力条件下的渗流平行试验。试验结果表明:当轴压、围压和气体压力恒定时,滑脱效应渗透率表现为,△K_(He,b)>△K_(CH_4,b)>△K_(N_2,b)>△K_(CO_2,b);基质变形渗透率表现为煤体对气体的吸附性越强,产生的基质变形渗透率越大,试验结果为△K_(He,s)<△K_(N_2,s)<△K_(CH_4,s)<△K_(CO_2,s);在轴压和围压一定条件下,滑脱效应渗透率、基质变形渗透率和有效渗透率均随气体压力的增大呈非线性变化。滑脱效应渗透率与气体压力关系式可表示为△Ki,b=ap~b;基质变形渗透率随气体压力的增加呈二次函数关系增大,即△K_(i,s)=ap~2+bp+c;有效渗透率随着气体压力的增加呈现出先减小后增大现象,具有明显的滑脱效应,且二者之间变化关系符合二次函数关系,即△K_(i,g)=ap~b+bp+c。
In order to investigate the effect of slippage effect and matrix deformation on the seepage characteristics of low permeability coal, the seepage flow parallel tests of four kinds of gas under different pressure conditions were carried out with the coal samples of 8 # seam in Yuyang Coal Mine as the research object. The experimental results show that when the axial compressive force, confining pressure and gas pressure are constant, the permeability of slippage effect is expressed as ΔK_ (He, b)> ΔK_ (CH_4, b)> ΔK_ (N_2, b) CO 2, b). The permeability of matrix deformation shows that the stronger the adsorption of coal on the gas, the greater the matrix deformation permeability. The experimental results are as follows: △ K_ (He, s) <△ K_ (N_2, s) K_ (CH_4, s) <△ K_ (CO_2, s). Under certain conditions of axial compression and confining pressure, the slippage effect, matrix deformation permeability and effective permeability all change nonlinearly with the increase of gas pressure. The relation between slippage effect permeability and gas pressure can be expressed as △ Ki, b = ap ~ b. The matrix deformation permeability increases quadratically with the increase of gas pressure, that is △ K_ (i, s) = ap ~ 2 + bp + c. The effective permeability decreases firstly and then increases with the increase of gas pressure, and has obvious slippage effect. The relationship between the two is in accordance with the quadratic function, that is, △ K_ (i, g) = ap ~ b + bp + c.