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Suppressing Axial-Torsional Coupled Vibrations in Drillstrings

Authors
  • Belem Saldivar

    Departamento de Control Automatico, CINVESTAV-IPN, Av. IPN No. 2508, Col. San Pedro Zacatenco, C.P. 07360, Mexico D.F.,Mexico

  • Sabine Mondie

    Departamento de Control Automatico, CINVESTAV-IPN, Av. IPN No. 2508, Col. San Pedro Zacatenco, C.P. 07360, Mexico D.F.,Mexico

  • Jean Jacques Loiseau

    Institut de Recherche en Communications et Cybernetique de Nantes, 1 rue de la Noe, BP 92101, 44321 NANTES cedex 3, France

  • Vladimir Rasvan

    Department of Automatic Control, University of Craiova, A.I.Cuza, 13 Craiova, RO-200585 Romania.

Abstract
In drilling operation, a wide variety of oscillations causing failures often arise. Torsional vibrations (stick-slip) are originated by the cutting device (bit) motion, these vibrations in turn excite axial oscillations causing a phenomenon known as bit-bouncing. This paper addresses two important challenges: the modeling of the coupled axial and torsional dynamics in a vertical oilwell drilling system and the design of an effective controller to reduce undesirable behaviors. Through the D'Alembert transformation, the distributed parameter model of the drillstring is reduced to a neutral-type time-delay equation which effectively describes the oscillatory behavior of the system. The Lyapunov theory allows to develop an efficient strategy for the control synthesis guaranteeing the elimination of the stick-slip and bit-bounce. This approach leads the "practical" stabilization of the closed loop system. All results can be easily generalized to any time-delay system subject to bounded disturbances. The effectiveness of the strategy is validated through simulations.
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Published
2013-03-27
Section
Articles