我国煤层普遍具有低透气性、高瓦斯含量的特性，在低透气性煤层增透方面，煤层注水、水力压裂、水力割缝等水力化技术得到了广泛应用，并取得了良好的瓦斯治理效果。然而水作为外侵液进入煤体，堵塞了瓦斯流动通道，降低了瓦斯解吸量，产生了水锁效应。为分析水力化技术造成水锁效应的内在机理，利用压汞实验分析了煤样孔容分布规律，以及利用扫描电镜分析了原始、饱水、饱CMC溶液煤样的微观结构，基于低场核磁共振技术研究了煤样在饱水状态以及饱CMC溶液状态下的液相滞留效应，并根据曲线相似度法分析了孔径与束缚流体饱和度的相似度。研究结果表明:CMC溶液可以溶解煤中的矿物质增加煤孔隙裂隙以及降低水在煤体表面的表面张力，从而达到解除水锁效应的目的;随着煤变质程度的增大，T₂截止值在逐渐减小，T₂截止值的数值与煤样孔径大小呈负相关;煤样的束缚流体饱和度远大于自由流体饱和度，煤样在饱水状态下的束缚流体饱和度比饱CMC溶液状态下高;高变质程度的煤大孔孔容少、微孔孔容多，使得水在煤孔隙中的毛细管力大，最终造成高阶煤的水锁效应严重;大孔孔容是影响束缚流体饱和度的主控因素，微孔起到正向促进作用，得到束缚流体饱和度S与大孔孔容V_A、微孔孔容V_D的耦合关系式:S=94.86-1 078.96V_A+261.24V_D。滞留在煤体内的束缚水阻塞了瓦斯流动通道，是造成水锁效应的根本原因，增加煤层的孔隙裂隙以及选用合适的表面活性是减缓煤层水锁效应的有效措施。

Coal seams in China generally have the characteristics of low permeability and high gas content. To improve the permeability of coal seams,water infusion,hydraulic fracturing,hydraulic slotting and other hydraulic technologies have been extensively used,which have good effects on gas control. However,When water enters the coal seam as an extravasation fluid,it blocks the gas flow channel,and reduces the volume of gas desorption,which results from the wa- ter blocking effect. In order to analyze the internal mechanism of water blocking effect caused by hydraulic technology, the pore volume distribution of coal samples was analyzed by mercury injection experiment,and the microstructure of raw,water saturated and CMC solution saturated GQ coal samples were analyzed by scanning electron microscope. The liquid phase retention effects of different coal samples saturated by water and CMC solution were studied by low field nuclear magnetic resonance (NMR) technique. According to the curve similarity method,the similarity between pore size and irreducible fluid saturation was analyzed. The results show that CMC solution can dissolve the minerals in coal matrix,which increases the coal pore fissure,and reduce the surface tension of water on the coal surface,which proves that adding CMC can relieve the water blocking effect. With the increase of coal metamorphism,the T2 cutoff value de- creases gradually,and the T2 cutoff value is negatively correlated with the pore size of coal sample,the irreducible fluid saturation of coal samples are much higher than that of free fluid saturation,and the irreducible fluid saturation of coal samples are higher than that of saturated CMC solution. The coal with high metamorphic degree has less macroporous volume and more micropore volume,which makes the capillary force larger,leading to serious water blocking effect in high metamorphic degree coal. The macroporous volume is the main control factor affecting the irreducible fluid satura- tion,and the micropore plays a positive role in promoting the irreducible fluid saturation. The coupling relationship be- tween the irreducible fluid saturation and the macroporous volume and the micropore volume is obtained as S = 94． 86-1 078． 96VA +261． 24VD . Retention of irreducible water in the coal blocks the gas flow channel,which is the root cause of water blocking effect. Increasing the pores and cracks in the coal seam and selecting the appropriate surfactants are the effective measures to relieve the water blocking effect of coal seam.