煤层顶板深孔“钻-切-压”预裂防冲技术试验研究

针对现有顶板定向水力压裂技术中缝槽预制工序繁琐、成缝质量差的问题,提出钻孔、高压水射流切缝、高压水力压裂(钻-切-压)一体化预裂顶板防冲技术,并在葫芦素煤矿进行了试验研究。试验结果表明:“钻-切-压”一体化技术与装备在不退钻杆的前提下能够进行人工切槽,并采用单孔后退式多次压裂,提高了施工效率;使用的对称双孔型高压射流器能够高效形成4~5 mm宽度的人工缝槽,增大了切缝效果,并降低了压裂时裂缝起裂压力,扩展了压裂半径,单轴抗压强度为50~60 MPa的顶板岩层,单次压裂半径最大可达15 m;“钻-切-压”技术弱化顶板使得巷道围岩应力水平降低,临空巷道附近高能微震事件数量大幅减少,微震频次和能量无急剧变化,保证了工作面顺利回采。

Experimental research on drilling-cutting-fracturing pre-fracturing to prevent rock burst technology for deep hole of roof of coal seam

In view of problems of complicated process of slot prefabrication and poor quality of seam formation in existing roof directional hydraulic fracturing technology,a technology of drilling,high-pressure water jet cutting and high-pressure hydraulic fracturing(drilling-cutting-fracturing)integrated pre-fracture roof to prevent rock burst was put forward,and experimental research of the technology in Hulusu Coal Mine was carried out.The experimental results show that thedrilling-cutting-fracturingintegrated technology and equipment can cut grooves manually without retreating drill pipe,and use single hole retreating multiple fracturing to improve construction efficiency.The symmetrical double hole high pressure jet device can effectively form a 4-5 mm wide artificial fracture groove to increase fracture cutting effect,reduce fracture initiation pressure,and expand fracture radius.The maximum single fracturing radius of roof strata with uniaxial compressive strength of 50-60 MPa can reach 15 m.Thedrilling-cutting-facturingtechnology weakens the roof and reduces the stress level of surrounding rock.The number of high-energy microseismic events near the goaf roadway has been greatly reduced,and the frequency and energy of microseismic events have not changed dramatically,so as to ensure the smooth mining of the working face.