Research On Thread Failure Of Pumping Unit Tubes And Preventive Measures

Petroleum industry is one of the pillar industries of our country,and the production of oil was plagued by the tubing failure accidents of pumping wells, which was the main factors affecting production. In recent years, the accidents of tubing failure is more and more, accounting for more than 26% of inspection well, which not only affected the oil production, but also caused huge economic loss. According to statistics, the threaded connection was the main failure part.Therefore, research on the tubing failure is very necessary.In this paper, the forms and mechanism of the tubing failure, loading conditions and the preventive measures are studied.The tubing failure forms are analyzed in this paper, including tubing fracture, thread gluing and thread puncture. Tubing failure has the greatest harm, mainly because of the influence of alternating load. Thread gluing is mainly due to excessive wear between the thread and the high contact stress.The low dimensional accuracy of thread results in thread puncture.The axial static load and dynamic load of tubing are analyzed and the expression of total axial load is established in this paper. The stress and deformation of thread are also studied. At the same time, the deformation coordination equation and axial force distribution are analyzed. Tubing and coupling model are created by SolidWorks, and deformation conditions of different thickness and different diameter of tubing are compared by the finite element analysis using ANSYS Workbench.Preventive measures are presented to reduce failure rate, including improving the repair precision, improving the way of installation and using thick tubing. By the experiment, radial plastic deformations are compared and the preventive measures are verified.