Gap element method and its application on force analysis of tubing strings

Liu Weikai, Song Mingxing, XU

Abstract

A static force model is set up for analyzing the dual layer contact between tubing strings featuring its actual work conditions. Dual layer gap element theory describes the frictions when the tubing strings are contacted, with its real contact each node of tubing strings reflects, the overall balance equation and its requirements for solutions can be given. Based on the force analysis, a section of tubing string is added on the bottom of the original strings for reducing the frictions, which a pre-added force is put under the artificial bottom hole that could reduce the average force of the tubing strings and elongate the life span of tubing strings.