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不同性质岩层间的弱接触面是影响边坡、地下巷道及硐室等岩土结构稳定的关键因素之一,煤层开采引起的覆岩运动是导致采动影响区内垂直页岩气井破坏的主要原因,针对垂直穿过长壁煤柱的页岩气井井筒稳定性问题,利用二维地质模型,对井筒剪切、离层、拉伸及压缩等变形量进行了预测,对比分析了层间弱接触面对穿煤层垂直页岩气井稳定性的影响;根据煤柱内不同布井位置条件下井筒各类变形的大小及轴向分布规律,得到了井筒沿轴向易于失稳的危险高度并优化了布井位置。结果表明,FLAC程序中的接触面单元能够很好地表征由采动引起的、沿软硬岩层间弱接触面出现的动力响应,对井筒的主要失稳模式——剪切失稳展现效果良好。
The weak contact surface between rock layers with different properties is one of the key factors that affect the stability of geotechnical structures such as slopes, underground tunnels and chambers. The overlying strata movement caused by coal mining is the main cause of vertical shale gas damage in the mining affected area Because of the stability of shale gas well vertically penetrating longwall pillars, the two-dimensional geological model is used to predict the deformation of wellbore shear, delamination, stretching and compression. The influence of the contact surface on the stability of the vertical shale gas well in the coal seam is discussed. According to the size and axial distribution of various deformation of the wellbore under different well locations in the coal pillar, the dangerous height of the wellbore prone to instability in the axial direction is obtained and optimized The cloth well location. The results show that the contact element in FLAC program can well characterize the dynamic response of mining interface caused by mining and weak contact between soft and hard rock formations, and shows a good effect on the main failure mode of the wellbore - shear instability .