Abstract: It is necessary to predict and control quantitatively the bit trajectory in directional drilling.For this reason it is very impratant to determine the values of the side forees,Pa controlling the inclination angle and P,controlling the azimuth angle of the borehale,v-hieh act an the bit in an assembly of a down hole motor with a bent-sub (BS-DHM).Whi1e a systematic analysis of BS-DHM is still lacking in literature,the authors have developed the beam-column theory for the analysis of BS-DHM.In this paper a new mechanical model of BS-DHM is established,A general equation about the continuous condition of a continuous beam-column is presented.

摘要： 对弯接头-井下动力钻具组合进行三维分析,可确定钻头上的变井斜力和变方位力,以满足对定向井井眼轨道进行定量预测和控制的需要,本文用纵横弯曲法建立了弯接头——井下动力钻具组合的力学模型,提出了关于连续条件的一般命题和处理弯接头弯角的两种等效方法,提出了等效钻铤假设并用力学实验方法确定动力钻具的等效抗弯刚度,推导了装置角为任意值时的计算弯角公式,建立了在三维井身条件下弯接头-井下动力钻具组合受力分析的普遍方程以及在一维、二维分析中的简化形式.这些结果可用来定量计算各种带有动力钻具的井底组合在各种井身条件下的钻头变井斜力和变方位力、钻头倾角、各点挠度、支点处内弯矩和转角值等.本文进一步分析了钻具结构参数、井身几何参数和工艺操作参数对钻头侧向力的影响,其中影响最大的是下部组合长度、弯角和装置角.现场验证证实了上述理论分析的正确性.

关键词: 定向钻井, 钻井理论, 钻柱力学, 钻具组合, 井眼轨迹, 钻头侧向力