Analysis of Drill String’s Vibration Characteristics Based on Sliding Mode-PI Controller

Abstract

Purpose: Drill string is the core component in drilling engineering, and studying drill string vibration is significant to reduce drilling costs and increase drilling efficiency. Methods: The control equation is derived by establishing the drill string’s axial–torsion–lateral coupled vibration model. Based on the fourth-order Runge–Kutta method and adaptive step method, a sliding mode-PI controller is designed to control and analyze the drill string system’s axial–torsional-lateral coupled vibration. Results: When the rotation speed increases, the drill string produces a strong backward whirl, and the drill tool is prone to failure. The sliding mode-PI control of the drill bit speed control can effectively suppress the whirl. Conclusions: The designed sliding mode-PI controller can suppress the drill string vibration and adjust the vibration to an allowable range. It can effectively predict the dynamic performance of downhole tools, ensure operation efficiency and reliability, and provide a basic reference for the drill string dynamics study and vibration control.