悬链线法是一种具有独特优点的定向钻井方法。本文在文献〔1〕的基础上,试图通过有关理论分析,对悬链线法钻定向井的一些问题提供参考。考虑到悬链线法钻定向井需要连续造斜,且井越深其井斜角愈大;同时还注意到岩石与钻头、钻头与钻柱的互相作用,本文提出了将钻头与岩石间的相互作用抽象为弹性抗转支承,即不约束转角的弹性嵌固端的设想(图4)。此外,在分析时假定井眼轨迹为一平面曲线,建立悬链线法钻定向井下部钻柱的三维挠曲变形的计算模型;提出了保证钻头沿预定井眼轴线(悬链线)的钻进条件:V′(o)=0,U′(o)=-tgθ。通过Laplace变换获得了该问题的解析解。文末以算例说明有关计算过程,并对所给结果进行了分析讨论。 Catenary method is a unique advantage of directional drilling method. Based on the literature [1], this paper attempts to provide some references for some problems of catenary drilling of directional wells by theoretical analysis. Considering that the catenary method for drilling directional wells needs continuous slanting, and the deeper the well is, the greater the inclination of the well is. Meanwhile, the interaction between the rock and the drill bit and the drill string is also noticed. In this paper, The interaction is abstracted as an elastic anti-rotation bearing, that is, an elastic locking end that does not constrain the corner (Figure 4). In addition, the well trajectory is assumed to be a plane curve in the analysis, and the calculation model of the three-dimensional deflection of the drillstring in the downhole part of the catenary is set up. A drill is proposed to ensure that the drill bit is along the axis of the wellbore (catenary) Condition: V ’(o) = 0, U’ (o) = - tgθ. An analytical solution of the problem is obtained by Laplace transform. At the end of this paper, an example is given to illustrate the calculation process, and the results given are analyzed and discussed.