The mechanisms leading to torsional vibrations in drilling systems are considered in this paper. Thereto, a drill string model of the axial and torsional dynamics is proposed, where coupling is provided by a rate-independent bit-rock interaction law. Analysis of this model shows that the fast axial dynamics exhibit an axial stick-slip limit cycle. This generates an apparent velocity-weakening effect in the torque-on-bit, explaining the onset of torsional vibrations. Based on this analysis, a strategy for control design aiming at the suppression of torsional vibrations is presented.
|Number of pages||6|
|Publication status||Published - 2011|
|Event||2011 IEEE International Conference on Control Applications (CCA) - Denver, United States|
Duration: 28-Sep-2011 → 30-Sep-2011
|Conference||2011 IEEE International Conference on Control Applications (CCA)|
|Period||28/09/2011 → 30/09/2011|