大直径地面钻井井身稳定特性分析及工程控制

Stability Characteristics Analysis of Large Diameter Surface Drilling Wellbore and Engineering Control

高强度开采条件下地面钻井受剧烈采动影响易破坏失效,运用有限差分程序FLAC3D对采动条件下不同直径钻井套管的受力进行了模拟计算,结果表明岩层分界面处套管变形较大,套管直径越大其变形和承受应力更小,钻井直径加大失效的风险降低。针对常规直径钻井在抽采过程中受采动影响发生严重破坏的问题,余吾煤业公司开展进行了大直径地面钻井抽采采空区瓦斯的工程试验,取得了良好的效果,现场试验结果表明采用大直径地面钻井可避免钻井完全失效,延长钻井抽采有效期。

Under the condition of high intensity mining,surface boreholes are easily damaged affected by severe mining. By using the finite difference program FLAC3 D,the force of different diameter well casing was simulated and calculated under the condition of mining. The results show that the casing deformation is larger at the interface of rocks. The larger diameter of the casing,its deformation and under-stress is smaller,and the drilling diameter is increased to reduce the risk of failure. According to the serious damage problem affected by mining,which occurred in the extraction process of the conventional diameter drilling,Yuwu Coal Company carried out engineering test of large-diameter surface drilling gob gas extraction and achieved good results. The field test results show that using large diameter surface drilling can avoid drilling complete failure and extend the validity of drilling drainage.