Abstract: This paper applies the non-linear finite element method to the prediction of the torque of the drill string and the drilling direction of the bit.Two non-linear problems are tackled, one being the large deformation of the string, the other the contact between the string and the wall of the wellbore.A group of equations are derived by the non-linear amalysis of the drill string, and the corresponding calculation software based on these equations are developed. The work of this paper has been successfully applied to the drilling practice in Weizhou, South China Sea, where Naihai West Oil Co., Ching National Offshore Oil Corporation, drilled 5 wells using the technique of this paper.

Key words: horizontal well, drill string force, friction force, torque, non-linear, FEM, prediction, computer, software

摘要： 在钻探水平井尤其是大位移水平井中,事先较准确地预测出钻柱的钻进扭矩及钻头前进的方向,是取得水平井成功的关键条件之一.文中探讨了非线性有限元在预测水平井钻井中的钻柱扭矩及钻头前进方向方面的应用.利用有限元理论,着重分析了水平井实际钻进中的钻柱大变形非线性及钻柱与井壁的接触非线性问题,导出了一套非线性有限元钻柱力学模式,在此基础上编制了一套非线性力学计算程序软件,并在海洋石油南海西部石油公司一个钻井平台水平井钻井进行了5口井的实际验证,获得了一些带启迪性的结论.

关键词: 水平井, 钻柱受力, 摩阻, 扭矩, 非线性, 有限元, 预测, 计算机, 软件