关于油井套管柱的屈曲问题虽已经有一些研究文献 ,但深入系统地研究该问题的文献并不多 ,由于其微分方程求解困难 ,各文献并没有给出一致的套管临界屈曲载荷 ;并且给出的结果普遍偏高。文章首次将套管和内、外部液体一起考虑 ,建立其微分方程 ,并用无穷级数法求解 ,得到了比较准确的临界屈曲载荷。论述了管柱内、外壁侧向液压对管柱发生屈曲的影响 ,对于开口管柱 ,当其处于微弯状态时 ,内、外壁侧向压力引起管柱任一截面的弯矩等于作用于底端的轴向力和沿轴线均匀分布的液柱重力所产生的弯矩。其结果可供油井设计和施工者参考 Although there is some research literature about the buckling problem of oil well casing string, there is not much literature on the systematic study of this problem. Because of the difficulty of solving differential equations, the literature does not give a consistent critical casing buckling load. The results given are generally high. For the first time, the article considers casing and internal and external liquid together, establishes its differential equation and solves it by infinite series method, and obtains more accurate critical buckling load. The effect of lateral hydraulic pressure on the buckling of the pipe string is discussed. For the open pipe string, when it is in the micro-bent state, the lateral pressure of the inner and outer walls causes the bending moment of any section of the pipe string to be equal to the moment End axial force and along the axis of the liquid column evenly distributed gravity moment. The result is available to oil well designers and constructors for reference