间隔切缝水力压裂提高综放顶煤回收率研究

Improving top-coal recovery rate of fully mechanized top-coal caving by interval slitting hydraulic fracturing

为了改善特厚坚硬顶煤冒放效果差的现象,以榆林地区神树畔煤矿3107工作面为研究现场,根据悬臂梁理论分析支架上方顶煤断裂的合理裂缝间隔,提出了该条件的顶煤竖直方向的裂缝间隔不宜太大,进而提出采用深孔水射流间隔切缝后压裂的方案,设计每组预裂孔水平间距10m,孔内间隔切缝距离7.5m,即竖直方向裂缝间隔2.6m,在工作面两巷超前布置水力压裂孔施工,避免了与工作面回采作业的干涉,施工后通过电磁波CT技术探测检验预裂效果。结果表明:深孔切缝间隔水力压裂能够在顶煤中使预裂缝扩展半径达6m左右,压裂后顶煤放出时没有大块,顶煤回收率显著提高,该技术为改善坚硬特厚煤层顶煤冒放性提供了一种有效的途径。

Aiming at the phenomenon that the caving effect of extra thick hard top coal is poor and difficult to be released,taking 3107 working face of Shenshupan Coal Mine in Yulin area as the research site,the reasonable crack interval of top coal fracture above the support is analyzed based on the theory of cantilever beam.It is suggested that the vertical crack spacing of top coal should be less than 2.8 m.Then,the scheme of hydraulic fracturing after deep hole water jet interval slitting is put forward.The distance between each group of presplitting holes is 10 m,the distance between the holes is 7.5 m,and the vertical crack spacing is 2.6 m.Hydraulic fracturing holes are arranged in advance in two working face ways,thus to avoid interferences with the working face mining operation.After construction,the effect of pre-cracking was tested by electromagnetic wave CT technology,and the results show that:the pre-cracking propagation radius can reach 6 m in top coal.After fracturing,no large lump coal was drawn out,and the recovery rate of top coal was improved.