Mitigation of torsional vibrations in drilling systems: a robust control approach

T.G.M. Vromen (Corresponding author), C.H. Dai, N. van de Wouw, T.A.E. Oomen, P. Astrid, A. Doris, H. Nijmeijer

Research output: Contribution to journalArticleAcademicpeer-review

17 Citations (Scopus)
1 Downloads (Pure)

Abstract

Stick-slip vibrations decrease the performance, reliability, and fail safety of drilling systems. The aim of this paper is to design a robust output-feedback control approach to eliminate torsional stick-slip vibrations in drilling systems. Current industrial controllers regularly fail to eliminate stick-slip vibrations, especially when multiple torsional flexibility modes play a role in the onset of stick-slip vibrations. As a basis for controller synthesis, a multimodal model of the torsional dynamics for a real drill-string system is employed. The proposed controller design strategy is based on skewed-\mu DK iteration and aims at optimizing the robustness with respect to uncertainty in the nonlinear bit-rock interaction. Moreover, a closed-loop stability analysis for the nonlinear drill-string model is provided. This controller design strategy offers several benefits compared with existing controllers. First, only surface measurements are employed, therewith avoiding the need for down-hole measurements. Second, multimodal drill-string dynamics are effectively dealt with in ways inaccessible to state-of-practice controllers. Third, robustness with respect to uncertainties in the bit-rock interaction is explicitly provided and closed-loop performance specifications are included in the controller design. Case study results confirm that stick-slip vibrations are indeed eliminated in realistic drilling scenarios using the designed controller in which state-of-practice controllers fail to achieve this.

Original languageEnglish
Article number8094252
Pages (from-to)249-265
Number of pages17
JournalIEEE Transactions on Control Systems Technology
Volume27
Issue number1
DOIs
Publication statusPublished - 1 Jan 2019

Keywords

  • μ-synthesis
  • drilling systems
  • output feedback
  • robust control
  • stick-slip oscillations.
  • stick-slip oscillations
  • μ-synthesis

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