定向井钻柱二维静力分析的间隙元法

TWO-DIMENSIONAL STATIC MECHANICAL ANALYSIS USING THE GAP ELEMENT METHOD IN DIRECTIONAL DRILL-STRING

定向钻井中的钻柱是一极细长梁,在各种载荷作用下产生弹性变形并受到井壁约束,属于接触非线性力学问题。作者通过构造双向接触摩擦间隙元把钻柱与井壁结合起来进行钻柱二维静力分析,该间隙元能正确描述钻柱与井壁的接触摩擦状态,具有较高的计算精度。运用本文方法可以快速(与三维静力分析相比)得到钻柱二维静力分析的结果,即钻柱和钻头的受力变形状态以及井底钻压和地而施加钻压之间的关系,为定向钻井提供理论依据。

The study of forces acted on the drill-string is the question of contact-nonlinear mechanics. A two-directional contact-friction gap elements was created using it to analyse drill-string two-dimentional static forces (DSTDSF) considered both drill-string and well-wall was conducted. The contact-friction states between drill-string and well-wall was described well by the gap element method, it presents higher calculational precision. Using the method, the calculation result of DSTDSF, including the deformed and forced states of drill-string and bit, and also the relationship between bottomhole pressure and surface pressure could be obtained more quickly in comparison with three dimensional static analysis by the same method. It is successful to put forward a theoretical foundation for directional well drilling.