间隙元在钻柱接触非线性力学分析中的应用

为了描述钻柱与井壁的接触摩擦非线性问题，构造了多向接触摩擦间隙元，并进行了理论公式推导，把多向接触摩擦间隙元与梁单元相结合，建立了钻柱接触和几何非线性有限元分析方法。经大庆油田GPl水平井应用表明，该方法能够求出钻柱在不同井深处的接触摩阻力，其井口悬重计算误差低于10％，为钻柱设计和现场施工提供了可靠的理论依据。

The application of gap element to the nonlinear mechanics analysis of drillstring

In order to describe the nonlinear contact between drillstring and hole wall, the multi-directional contact gap element (MCGE) is constructed and its formulas are derived. Through the MCGE connection with the beam element, the contact and geometric nonlinear finite element of drillstring is obtained in this paper. The application of this method to the GP1 well in the Daqing oil field shows that the contact friction force of the drillstring at any well depth can be obtained and the calculating error of the hole top load is below 10%. The results may provide a theoretical basis for the design and operation of drillstring.