Shock vibration response characteristic of perforating tubing string in ultra-deep wells

Abstract

During perforating operation in ultra-deep wells, the massive shock wave caused by a perforating charge's instant explosion, will trigger violent vibration behavior of the tubing string, causing damage to the tool string. Based on Hamilton's principle, taking into account the impact of perforation detonation load, tubing-casing contact, and high temperature and pressure environment in ultra-deep well, the axial-lateral-torsional coupling nonlinear dynamics model of tubing string system was established and solved by the finite element technology combined with Newmark-β method, based on which the corresponding calculation program was developed. The effectiveness of this model and program was verified by the field test data of an actual well in southwest China. The influence mechanism of main perforation parameters on shock vibration of tubing string in ultra-deep wells was studied by using the nonlinear dynamic model, and it was found that proper placement of shock absorbers can effectively reduce the dynamic force in the tubing string, the reasonable layout range of shock absorber should be about 20–25 m. The optimal outer diameter of tubing is between 0.889 and 0.100 m. The proper outer diameter of perforating gun is between 0.135 and 0.150 m. The ideal tubing length is 150–170 m. The optimum charge of perforating charge is about 15 g. The research results can be used to design perforating stool string, and provide theoretical support for reducing the risk of premature failure of tubing string.