中文摘要：

我国煤矿煤层透气性系数低、抽采难度大，严重制约着矿井的安全高效生产。水力压裂因其增透效果显著，被广泛使用，但井下钻孔水力压裂存在压裂裂缝类型单一、压裂钻孔抽采寿命短、不均衡，易垮塌、堵塞，后期裂缝导流能力不足等问题，为改进完善已有井下水力压裂技术，文章结合中马村煤矿实际情况，引入石油开采领域的重复水力压裂技术，探讨了井下钻孔重复水力压裂的原理、类型及裂隙体系的形成，并通过现场应用取得了较好的效果。

英文摘要：

The low permeability coefficient of the seam and the high difficult gas drainage in China coal mine have seriously restrict the mine safety and high efficient production. The remarkable permeability improved effect of the unitary hydraulic fracturing was widely applied. The problems of the fractured crack type, short service life of the gas drainage in the fractured borehole, unbalance, easy collapse, jamming, insufficient flow capacity of late crack were existed in the underground hydraulic fractured borehole. In order to improve the hydraulic fracturing technology in underground mine, in combination with the mine actual conditions, a repeated hydraulic fracturing technology was introduced from the oil mining industry. The paper tried to discuss the principle and type of the borehole repeated hydraulic fracturing in the underground mine and the formation of the crack system. Good effects were obtained from the site applications.