清洁压裂液与水对煤层渗透率影响对比试验研究

针对煤矿井下采用不同压裂液增加煤层透气性的工程问题，开展了多组有效应力作用下烘干、含水与含清洁压裂液3种煤样的渗透率对比试验，并利用多孔介质和流体力学理论分析了压裂液影响煤层渗透率的机理。研究结果表明：饱和清洁压裂液煤样渗透率比饱和水煤样渗透率平均高出177.83%，随着有效应力增加，煤样渗透率均呈指数关系降低；压裂液对煤层渗透率的影响受表面张力影响，表面张力大，液体会在煤体内占据更多瓦斯运移通道，从而降低煤层透气性，与清水相比，清洁压裂液有效降低了煤体内部孔隙表面液体张力，增大了瓦斯运移通道，提高了煤层渗透率，有利于煤层气的抽采。

Comparative experiment on influence of clear fracturing fluid and water on coal seam permeability

Different fracturing fluids are normally used to improve the seepage property of coal seam in underground coal mines.This paper conducted the comparative permeability test on three kinds of coal seams with drying water，water and clear fracturing fluid.The influence of fracturing fluid on the permeability of coal seam was analyzed using porous medium and fluid mechanics theory.The results show that:the permeability of coal samples saturated with clear fracturing fluid is higher than the permeability of coal samples saturated with water by an average of 177.83%，and the permeabilities of all these coal samples decrease exponentially with the increase of effective stress.The effectiveness of fracturing fluid on coal seam permeability is affected by surface tension.With the increase of surface tension，fluid will occupy more gas migration channel in coal body，thereby reduce coal seam permeability.Comparing with water，clear fracturing fluid in inner pore reduces the surface tension effectively，which can increase the gas migration channel and improve the permeability of coal seam.Clear fracturing fluid is favorable to the drainage of coal bed methane.