煤矿井上下联合抽采瓦斯关键技术研究及应用

Research and Application of Key Technology of Combined Gas Extraction Up and Down Well in Coal Mine

为解决煤矿井下压裂增透效果较差难以高效抽采瓦斯的问题,提出了煤矿井上下联合抽采瓦斯的模式,建立了基于地面井与井下钻孔抽采的方法;利用地面老井和井下钻孔通道,形成了一套长距离、多拐弯、大排量及可携砂的地面压裂井下对接技术。获得了水力压裂裂缝破裂扩展规律,给出了不同条件下煤层水力压裂裂缝形态,得到了压裂半径理论计算公式。提出了井上下联合地面井位置优选原则,给出了基于井上下联合的水力压裂设计方案。在寺河矿开展了井上下联合2个压裂孔的增透抽采试验,试验结果表明:1#压裂孔累积抽采量为50.31万m^(3),2#压裂孔的顺层考察孔2和顺层考察孔3抽采瓦斯纯量分别为238.35万m^(3)和129.29万m^(3),压裂孔及对比考察孔抽采效果分别提高6.34倍、43.8倍及31.37倍,压裂后平均抽采量比原始钻孔提高33.14倍,压裂后煤层具有较好的增透抽采效果。实现了井上下联合抽采瓦斯,对于同类型的矿井具有较好的指导价值。

In order to solve the problem that the effect of fracturing and permeability enhancement in coal mine is poor and it is difficult to extract gas efficiently,a mode of combined gas extraction in coal mine is proposed,and a method of gas extraction based on surface and underground drilling is established;a set of surface fracturing downhole docking technology with long distance,multiple bends,large displacement and sand carrying capacity has been formed by using the surface old wells and downhole drilling channels.The fracture propagation law of hydraulic fracturing fracture is obtained,the fracture shape of coal seam hydraulic fracturing under different conditions is given,and the theoretical calculation formula of fracture radius is obtained.The principle of optimizing the surface well location of the combination of up and down wells is proposed,and the hydraulic fracturing design scheme based on the combination of up and down wells is given.An enhanced permeability extraction experiment was conducted in Sihe mine by combining two fracturing holes above and below the well.The test results showed that the cumulative extraction volume of No.1 fracturing hole was 503100 m^(3),and the pure gas extraction volume of No.2 fracturing hole's bedding inspection hole 2 and bedding inspection hole 3 was 2.3835 million m^(3)and 1.2929 million m^(3),respectively.The extraction efficiency of the fracturing hole and comparative inspection hole increased by 6.34 times,43.8 times,and 31.37 times,respectively,the average pumping volume after fracturing is 33.14 times higher than that of the original hole.The fractured coal seam has better enhanced permeability pumping,realizing the combined pumping of gas above and below the well.It has realized the combined gas extraction up and down the well,which has good guiding value for the same type of mine.