水力压裂是改善煤层渗透率的常用方法，其改造效果直接影响煤层气井的产能。详细观测了西山煤田屯兰区块5口煤层气井的井下揭露煤层及裂隙展布情况，并联合体视镜、扫描电镜和显微CT等研究煤体结构、微裂隙、石英砂和煤粉的分布特征，结合区域地应力和水力压裂施工参数，剖析煤层气井的压裂效果。研究结果表明：水力压裂产生的宏观裂隙形态复杂多样，包含水平型、垂直型、X型和T型。距离煤层气井筒越近，煤体越破碎，以碎裂煤和碎粒煤为主，水力压裂裂隙发育，远离煤层气井筒的煤体主要是原生结构煤，以原生裂隙为主。石英砂主要铺置在水平裂隙内，仅有少量分布在T型裂隙内。石英砂与煤的裂隙面强烈摩擦、碰撞和嵌入，与压裂液破裂煤体叠加形成大量煤粉，造成煤粉裹挟石英砂堵塞裂隙。宏观裂隙内的煤粉主要受水力压裂时煤体破裂、压裂液冲刷煤体及石英砂与裂隙面摩擦而产生，微观裂隙内的煤粉在煤体破断时产生。煤粉与石英砂混合堆积在裂隙内，对携砂液产生巨大阻力，造成石英砂无法向煤层气井的远端运移。地应力的大小和方向、煤层及顶底板的强度是影响水力压裂裂隙张开与延展方向的重要因素，携砂液黏度低无法悬浮石英砂，容易造成石英砂与煤粉聚集堵塞裂隙。

Hydraulic fracturing is a widely used technique for increasing the permeability of coal seams. Its impact on the production capacity of coalbed methane(CBM) wells is significant. This paper makes detailed observations on the exposed coal seams and fracture distribution of 5 CBM wells in Tunlan block of Xishan coalfield, and studies the distribution characteristics of coal structure, microfractures, quartz sand and coal fine by using stereoscopic microscope, scanning electron microscope, and micro CT. The fracturing effect and influencing factors of CBM wells are analysed by combining regional geostress and hydraulic fracturing construction parameters. The research results indicate that the macroscopic fractures morphology produced by hydraulic fracturing are complex and diverse, including horizontal, vertical, X and T-shaped fractures. The degree of coal body fragmentation increases with distance from the CBM well. The coal body closer to the CBM well is mainly composed of fragmented and granular coal, while the coal body further away is mainly composed of undeformed coal with primary fractures. The quartz sands are mainly deposited in horizontal fractures, with only a small amount in T-shaped fractures. Quartz sand rubs, collides, and embeds strongly with the coal fracture surface. The fracturing fluid is then superimposed to fracture the coal body, resulting in a large amount of coal fines. This causes the coal fines to wrap around the quartz sand and block the fractures. The coal fines within the macroscopic fracture are primarily a result of the fracturing of the coal body, the flushing of the coal body by fracturing fluid, and the friction between the quartz sand and the fracture surface during hydraulic fracturing. Coal fine generation in micro-fractures during coal body fracturing. Coal fines and quartz sand accumulate in the fractures, creating enormous resistance to the carrying fluid and preventing the quartz sand from migrating to the far end of the CBM well. The magnitude and direction of the geostress, as well as the strength of the coal seam roof and floor, are important factors that influence the opening and direction of the hydraulic fracturing fractures. The low viscosity of the carrying fluid cannot suspend quartz sand, and the accumulation of quartz sand and coal fine can block the fractures, easy to cause quartz sand and coal fine to aggregate and block fractures.