井底地带应力应变场实验研究

离井底较远的上部井眼受力分析可简化为平面应力。离井底较近时,由于"端面开挖效应"就是三维力学问题,对此目前尚无解析解。通过实验,得出一些规律性的认识。地下双向水平应力相同时,水平应力同步增大或减小,对井底地带的稳定性不会有很大的影响;双向水平应力不同时,随着差异的增大,井底岩石各向异性程度增大,钻头向最大水平主应力方向的漂移趋势增强。

LABORATORY RESEARCH OF STRESS AND STRAIN FIELD UNDER BOTTM OF BOREHOLE

The forces analysis around borehole can be implicated as plane stress problem in upper bottom of hole, but when nearby bottom of hole, the problem is 3D mechanics because of "end face dugging effect" which has not analytic solution. Through experiment, some regular phenomenon has shown when two horizontul stresses are equal, the stabilization nearby bottom of hole cannot be affected. If the two horizontal stresses are different, the degrees of rock anisotropism under bottom is increased as long as difference increased, so that bit drift towarding maximum horizontal direction.