关键词: 油井, 管柱, 摩擦力, 变形, 受力分析

Abstract: The dynamic equations of helically buckled pipe string in vertical wells are a group of high order nonlinear ordinary differential equations,which describe the axial force distribution and deformation behavior of pipe.This paper acquires the asymptical helix solutions of the nonlinear equations under a symmetric condition;presents the influence of frictional coefficient on the axial force distribution along the pipe,the locations of nutral point and lock-up point,and the lock-up force etc.,derives the formulae to determine the neutral point,the lock-up point and the lock-up force.The correlation of the frictional coefficients and the axial force distribution is presented in curves,neutral point and lock-up point varying with the axial force acting on the top or bottom end are also shown in the curves.The results in this paper can be practically used for pipe string design and operational parameter selection for HPHT deep well down hole operations.

Key words: oil well, pipe string, frictional force, deformation, force analysis