低渗透突出煤的瓦斯渗流规律研究

 为了解低渗透突出煤体的瓦斯渗流规律，利用自行研制的煤岩体三轴渗透仪，在不同轴压和围压条件下，对以南桐矿区矿井低渗透突出煤层的原煤而制备的试样采用稳态渗流法进行瓦斯渗流试验；比较传统的渗透率计算方法与考虑瓦斯渗流的Klinkenberg效应的渗透率拟合方法在低渗透煤体渗流试验数据处理中的差异。研究结果表明：(1) 低渗透煤体中的瓦斯渗流具有显著的Klinkenberg效应；(2) 对于低渗透煤体，Klinkenberg系数b值与煤体的绝对渗透率呈显著的幂函数关系，而煤体的绝对渗透率与体积应力呈显著的二次多项式函数关系；(3) Klinkenberg系数b值随着煤体绝对渗透率的降低而逐渐增大，煤体的绝对渗透率随着煤体体积应力的增大而逐渐降低；(4) 采用考虑瓦斯渗流的Klinkenberg效应的渗透率拟合方法处理试验数据所得到的结果更为合理；(5) 试验得到的煤体渗透率表达式反映了瓦斯压力和应力对瓦斯渗流的共同作用，能很好地模拟低渗透煤层的瓦斯渗流。

INVESTIGATION ON LAW OF METHANE GAS FLOW IN COAL WITH COAL-GAS OUTBURST HAZARD AND LOW PERMEABILITY

For knowing the law of methane gas flow in coal with coal-gas outburst hazard and low permeability (CCOHLP),an experimental study of methane gas flow in coal samples,produced by raw CCOHLP from a coal mine at Nantong coalfield,is performed with self-developed triaxial load system and by way of steady-state flow under different confining pressures. It presents the comparison of test data on methane gas flow in CCOHLP processed by the traditional method of computing permeability and the method of fitting permeability with Klinkenberg effect. It is proved by experiments and numerical simulation that:(1) the Klinkenberg effect of methane gas flow in low permeability coal is especially prominent;(2) for the low permeability coal,the Klinkenberg coefficient b and the absolute permeability is related to a power function;meanwhile,the absolute permeability and bulk stress is related to a quadratic polynomial function;(3) the Klinkenberg coefficient b increases gradually with the decreasing absolute permeability;meanwhile,the absolute permeability decreases gradually with the increasing bulk stress;(4) the processing results of test data are with reason by the method of fitting permeability considering Klinkenberg effect;and (5) the algebraic expression on effective permeability of low permeability coal obtained by this experiment reflects the combined impact of gas pressure and stress on methane gas flow and it is able to simulate the methane gas flow in CCOHLP.