低透气性煤层点式酸化压裂增透技术研究与应用*

为解决富含矿物质煤层透气性问题，基于点式压裂和酸液增透煤体机制，提出点式酸化压裂增透技术，通过扫描电镜试验确定适合三元煤矿酸液配比体系。结果表明:点式酸化压裂钻孔组平均抽采瓦斯流量和浓度是普通钻孔组的3.65，1.72倍，是点式水力压裂钻孔组的1.32，1.06倍；点式酸化压裂增透效果明显优于点式水力压裂；且其增透煤体起裂压力和同等条件下注液量均低于点式水力压裂，点式酸化压裂实现煤体定点、低流量、大范围、快速增透，通过将物理增透与化学增透相结合，可有效提高煤体孔隙-裂隙结构发育程度和整体连通性，有助于煤体中瓦斯运移，提高采收率。

Research and application of point acidizing fracturing permeability improvement technology in low permeability coal seam

In order to solve the problem of permeability for the coal seam rich in minerals,based on the mechanism of point fracturing and acid solution permeability improvement for coal body,a technology of point acidizing fracturing permeability improvement was put forward.The acid solution ratio suitable for Sanyuan coal mine was determined through the scanning electron microscope (SEM) test.The field test results showed that the average drainage gas flow and concentration of point acidizing fracturing drilling group were 3.65 times and 1.72 times of that of ordinary drilling group,and they were 1.32 times and 1.06 times of the point hydraulic fracturing drilling group.The permeability improvement effect of the point acidizing fracturing was obviously better than that of the point hydraulic fracturing,and both the starting fracture pressure of the permeability improvement coal body and the liquid injection volume under the same conditions were lower than those of the point hydraulic fracturing.The point acidizing fracturing realized the fixed-point,low flow,large range and rapid permeability improvement of the coal body.The combination of physical and chemical permeability improvement methods greatly improved the development degree of coal pore-fracture structure and its overall connectivity,which is conducive to the gas migration and efficient drainage in the coal.