冲击地压关键层远程区域水力压裂防治技术

Control technology for critical rock burst formations by distant and large scale hydraulic fracturing

摘要:

针对我国目前冲击地压防治工程人员身处冲击危险区域，无法实现区域先行、超前治理的局面，论文提出了矿井冲击地压关键层远程钻孔水力压裂防治技术。分析了我国冲击地压矿井的地质条件和近几年重大冲击地压灾害的特点，认为华北石炭—二叠系煤田和侏罗系煤田很多冲击地压煤矿煤层上覆地层，普遍发育厚层坚硬的砂岩关键层，能量的释放符合冲击地压形成的“3因素”理论。经论证，关键层脆性强，硬度大，易于压裂，利用水力压裂法解除地应力是合适的；井下长钻孔、地面深孔和地面导斜钻孔的施工技术和钻孔水力压裂技术已成熟，实现远程钻孔水力压裂区域性的防治冲击地压是可行的。工业性试验显示，井下长钻孔顺层分段水力压裂长度可达800 m，水压可达40 MPa，裂缝半径为40 m；地面垂直钻孔分段压裂深度可达3000 m，压裂段高>100 m，压力达80 MPa，裂缝半径为100~200 m；地面导斜钻孔水平顺层段长度达1000 m，压力达80 MPa，裂缝半径为100~150 m；压裂前后煤体应力或支架压力的检测数据对比显示，压裂后的应力较压裂前降低了10 MPa以上，满足区域治理的要求，钻孔远程水力压裂在防治冲击地压上较传统方法具有显著超前优势、区域优势、效率优势、安全优势和环保优势，可以做到冲击地压防治区段的无人化，满足区域先行、超前治理的国家要求。

关键词:冲击地压;远程治理;水力压裂;区域防治;关键层;钻孔压裂

Abstract:

In view of the situation that rock burst control workers still work in hazardous areas underground， and the requirement that regional control of rock burst goes ahead of underground works cannot be met， the technology for key formation treatment by distant hydraulic fracturing through boreholes to relieve rock burst is put forward. By analyzing the geological conditions in the coal mine threatened by rock bursts and the hazardous characteristics of rock bursts happened in the resent years， it is understood the critical rock burst formation of massive hard rock is commonly developed in the roof of the coalbed， and the energy release in rock burst hazards meets the requirements of the “3 factors” theory on rock burst in north China C-P coal field and Jurassic coal field. According to rock mechanic analysis， the hard and brittle critical formation is easy to fracture. The technology to release rock stress in the key formation by hydraulicly fracturing is suitable. Since drilling technologies for underground long boreholes， deep holes and directional holes from surface have been technically proven， distant rock burst control in large scale by hydraulic fracturing in long borehole is feasible. The industrial tests showed that underground long borehole can be stage?-fracture up to 800m at 40MPa with fracture half-length upto； the vertical borehole drilled from surface can be as deep as 3000m with fracture segment greater than 100m at hydraulic pressure of 80MPa with fracture half-length about 100~200m long； the surface directional borehole can be drilled wi the inseam section as long as 1000m with hydraulic up to 80MPa with fracture half-length about 100~150 m. Analysis showed the pressure on coal seam or on shelf after fracturing was about 10MPa less than that before fracturing. Compared with conventional methods， the technology for key formation treatment by distant hydraulic fracturing through boreholes to release rock burst distantly have many advantages in regional and ahead control， engineering efficiency， safety and environment protection. The unmanned condition in the area threatened by rock burst can be realized in the hazard controlling process， and the requirement of regional and ahead control can be met.

Key words:rock burst;distant control;hydraulic fracture;regional prevention;key formation;borehole fracture