重复水力压裂技术在深井低透气性煤层中的应用

随着井下煤矿开采深度的不断加大,煤层透气性进一步降低,煤层瓦斯抽采难度亦同时增加,对于单一无保护层煤层来说,大多数需要人为地增加渗透率,水力压裂因其增透范围广,性价比相对较高而取得广泛的应用。对于深井低透气性煤层来说,为了进一步提高瓦斯抽采效率,单次的水力压裂增透技术已然不能满足需要,因此提出了井下重复水力压裂技术,并且论述了重复压裂原理及工艺流程。根据十二矿己_(15)-31040工作面地质情况,设计了相关水力压裂参数,并进行了重复水力压裂和压裂之后瓦斯抽采的效果检验。结果表明:煤层经过重复水力压裂后,煤层残余瓦斯含量较单次压裂降低明显,而且瓦斯抽采浓度和纯量亦增加显著。试验结果表明重复水力压裂可以明显提高深井低透气性煤层瓦斯抽采效率,具有一定瓦斯防治的应用价值。

Application of repeated hydraulic fracturing technology in deep well low permeability coal seam

With the increasing depth of underground coal mining, the permeability of coal seam decreases further, the difficulty of gas extraction is also increased, the anti-reflection technology of single hydraulic fracturing has been unable to meet the demand. In order to further improve the efficiency of gas extraction, the downhole repeated hydraulic technology is put forward, and the principle and technological process of repeated hydraulic are discussed. According to the characteristics of geology and coal seam in No.12 Mine of Pingdingshan Coal Mining Ji15-31040 face, the key technical parameters of repeated hydraulic fracturing were designed, and repeated hydraulic fracturing test and fracturing effect test were carried out. The results show that after repeated hydraulic fracturing of coal seam, the residual gas content of coal seam decreased significantly compared with that of single fracturing, and the concentration and quantity of gas extraction also increased significantly. The test results show that repeated hydraulic fracturing can significantly improve the gas extraction efficiency of deep well low-permeability coal seam, which has certain application value of gas prevention.