The development of coalbed methane not only ensures the supply of natural gas but also reduces the risks of coal mine accidents. The micropore structure of coalbed methane reservoir affects the seepage of coalbed methane; improvement of pore structure is one of the effective methods to enhance the efficiency of coalbed methane exploitation. In this study, low-pressure nitrogen gas adsorption, specific surface area analysis, nuclear magnetic resonance spectroscopy, and centrifugation experiment were used to evaluate the effect of ethanol on coal microscopic pore structure and fluid distribution during hydraulic fracturing. Seven coal samples were collected from the No. 3 coal seam in Zhaozhuang Mine, Qinshui Basin. The samples are mainly composed of micropores, transition pores, and mesopores. The experimental results show that ethanol can significantly change the pore structure by increasing the pore diameter. The average specific surface area, pore volume, and pore diameter of rock samples before ethanol immersion are 1.1270 m2/g, 0.0104 cm3/g, and 14.20 nm, respectively. The three parameters of rock samples after ethanol immersion are 0.5865 m2/g, 0.0025 cm3/g, and 29.37 nm. Ethanol improves the connectivity between micropores and mesopores. The average irreducible fluid saturation of samples saturated with formation water after centrifugation is 86%, and the average irreducible fluid saturation of samples soaked in three concentrations of ethanol solution decreases. It is considered that an ethanol solution of 0.4% concentration has the best effect on improving the pore structure and fluid distribution.

中文翻译：

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乙醇对煤层气储层微孔结构及流体分布影响的实验研究

煤层气的开发，既保证了天然气的供应，又降低了煤矿事故的风险。煤层气储层微孔结构影响煤层气渗流；改善孔隙结构是提高煤层气开采效率的有效方法之一。本研究采用低压氮气吸附、比表面积分析、核磁共振波谱、离心实验等手段，评价乙醇对水力压裂过程中煤微观孔隙结构和流体分布的影响。沁水盆地赵庄矿3号煤层共采集7个煤样。样品主要由微孔、过渡孔和介孔组成。实验结果表明，乙醇可以通过增加孔径来显着改变孔结构。乙醇浸泡前岩石样品的平均比表面积、孔容和孔径分别为1.1270 m2/g、0.0104 cm3/g和14.20 nm。乙醇浸泡后岩石样品的三个参数为0.5865 m2/g、0.0025 cm3/g和29.37 nm。乙醇改善了微孔和中孔之间的连通性。离心后地层水饱和样品的束缚流体平均饱和度为86%，浸泡在三种浓度乙醇溶液中的样品束缚流体饱和度平均降低。认为0.4%浓度的乙醇溶液对改善孔隙结构和流体分布的效果最好。