Friction-induced Torsional Vibrations in an Experimental Drill-String System

N. Mihajlović, A.A. van Veggel, N. van de Wouw, and H. Nijmeijer (The Netherlands)


Discontinuous friction model, bifurcation diagram, nonlin ear system, parameter estimation, torsional vibrations


In this paper, we aim for an improved understanding of the causes for torsional vibrations in rotary drilling systems that are used for the exploration of oil and gas. For this purpose, an experimental drill-string set-up is considered. In that system, torsional vibrations with and without stick slip are observed in steady-state. In order to obtain a pre dictive model, a discontinuous static friction model is used. The parameters of the suggested model are estimated and the steady-state behaviour of the drill-string system is anal ysed both numerically and experimentally. A comparison of numerical and experimental bifurcation diagrams indi cates the predictive quality of the model. Moreover, spe cific friction model characteristics can be linked to the ex istence of torsional vibrations with and without stick-slip.

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