低透气性煤层高压水力压裂-冲孔联合增透技术研究及应用

Research and application of combined antireflection technology of high pressure hydraulic fracturing and punching in low permeability coal seam

针对深部开采煤层普遍存在的构造应力复杂、透气性系数低、抽采效果差等问题,为探究最优的瓦斯抽采技术方案,以水溪煤矿K_(1)松软煤层为研究对象,分别采用水力压裂、水力冲孔、普通抽采和高压水力压裂—冲孔联合增透4种技术,进行现场对比应用试验。结果表明:高压水力压裂—冲孔联合增透技术对煤层透气性系数的提高程度分别为水力压裂、水力冲孔和普通抽采方案的1.85、1.61、6.30倍,抽采瓦斯纯流量分别提高了1.42、1.33、2.32倍,此外,抽采汇总瓦斯浓度(CH_(4)体积分数)保持在42.6%以上,抽采效率为四者之中最高。现场应用结果表明,高压水力压裂—冲孔联合增透技术具有明显的技术优势。

Aiming at the problems of complex structural stress,low permeability coefficient and poor extraction effect in deep mining coal seam,in order to explore the optimal gas extraction technology,taking K_(1) soft coal seam of Shuixi Coal Mine as the research object,four technologies including hydraulic fracturing,hydraulic punching,conventional pumping and high pressure hydraulic fracturing and punching combined antireflection were successively used to carry out the field pumping comparative application tests.The results show that:the improvement degree of permeability coefficient of coal seam by the combined antireflection technology of high pressure hydraulic fracturing and punching is 1.85 times,1.61 times and 6.30 times of that of hydraulic fracturing,hydraulic punching and ordinary test scheme respectively,the extraction pure gas flow increases by 1.42 times,1.33 times and 2.32 times respectively.In addition,the total gas concentration(methane volume fraction)remains above 42.6%,and the extraction efficiency is the highest among the four.The field application results show that the combined antireflection technology of high pressure hydraulic fracturing and punching has obvious technical advantages.