井下定向长钻孔水力预裂顶板防治强矿压技术研究与应用

Research and Application of Technology of Advance Hydraulic Fracturing of Roof with Underground Directional Long Boreholes for Relief of High Mine Pressure

为了解决神东矿区坚硬顶板和上覆遗留煤柱及埋深大于400m带来的强矿压问题,以布尔台煤矿42煤层为研究对象,采用数值分析、工程应用等方法,研究了坚硬顶板和过上覆集中煤柱强矿压灾害发生机理,研发了井下坚硬顶板定向长钻孔分段水力压裂超前弱化治理技术,对压裂目标层位选择、钻孔布置、压裂段间距、泵注排量、钻孔数量等参数进行研究和优化,采用孔内窥视、音频电透视、孔内瞬变电磁、压裂施工数据分析等手段对压裂裂缝进行监测,采用矿压数据分析、顺槽应力监测及变形特征分析等方法对强矿压治理效果进行评价,并在布尔台煤矿典型工作面进行了工程应用。应用结果表明:对坚硬顶板实施水力压裂治理后,与未治理区域相比,来压步距、动载系数、最高压力较未压裂区域分别降低了20.00%~69.70%、5.79%~7.90%、13.44%~18.64%,顺槽围岩应力降幅为22.22%~32.05%;上覆应力集中煤柱进行压裂卸压弱化后,顶板来压步距、动载系数、最高压力分别降低13.58%、13.77%、25.49%。定向长钻孔分段水力压裂超前弱化治理技术解决了强矿压灾害治理难题,取得了良好效果。

To relieve the high mine pressure caused by the hard and rigid roof,the left overlying coal column and the depth over 400 m,targeting the coal seam 42 of Buertai Coal Mine as subject,the mechanism that the hard and rigid roof,and the left overlying coal columns cause high-pressure disasters,is investigated,the technology of drilling long directional boreholes to hydraulically fracture the underground hard/rigid roof for the purpose of advance relief of high mine pressure is developed,parameters such as selection of layers to be fractured,borehole layout,interval between segments to be fractured,pump flow rate and number of boreholes etc.,are investigated and optimized,fractured fissures are monitored with such means as intra-borehole peep,audio-frequency electrical penetration,intra-borehole transient electromagnetic,and analysis of data from fracturing etc.,the result of control and prevention of high pressure are assessed with methods such as analysis of pressure-related data, monitoring roadway stress and analysis of deformation features,and the technology is practically applied to typical working faces of Buertai Coal Mine. The results forfo mth eth ew eaipghptliicnagti,o nth esh odwysn atmhiact,fafoctro rt hea ndha rtdh/eri gimda xr.o ofp rtersesautreed dwriotphs thbey h2 y0 d.r0 a0 u^li6 c9.f7 r0 ac%t ur,in 5 g.7,9 t^h7 e. 9 s0 t ep% piatnchd13.44~18.64% than those not treated,the stress in wall rock in roadway cuts by 22.22~32.05%;after the overlying stress-concentrated coal columns are relieved by fracturing,the roof’s step pitch of weighting,dynamic factor and max. pressure drop by 13.58,13.77 and 25.49% respectively. The technology of long directional boreholes for hydraulic fracturing by segments for advance relief solves the challenge of high-minepressure disasters,obtaining good effect.