Nonlinear stochastic drillstrings vibrations: Parametric study for stick-slip suppression

Abstract

Unstable vibrations caused by the transition between static and kinetic frictions produces stick-slip motions which is one of the primary causes of poor drilling efficiency and mechanism failure in the drilling process. Coupled lateral and torsional drill string dynamics are explored numerically and experimentally within this article. A reduced order model able to capture the non-linear responses, observed during dry-friction whirling, is presented along with scaled experimental apparatus tests. To reduce stick-slip oscillations, the control strategies are mostly focused on the angular velocity of the upper part of the drill string, the torque on bit and the torque of friction. These parameters are investigated, and the simulation results are seen to be in good agreement with experimental observations.