Local instability of rotation of a drill string

Authors

  • Belyaev A.K. Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, St. Petersburg, Российская Федерация

UDC

534.1

Abstract

Stability of a flexible drill string rotating in a curved oil well is studied. The string is considered as an elastic Cosserat bar, general equations are derived and the cases allowing for the closed form solution are analyzed. The rotation with constant angular velocity is shown to be feasible only for a straight shaft. In all other cases the rotation is unstable and for some relations between the parameters it is accompanied by quasi-static transition to a new configuration. The instability is caused by the energy exchange between the torsional and bending modes. The increasing torque on the end of the shaft improves the rotational stability at expenses of the increasing stresses in the drill string.

Keywords:

drill string, Cosserat curve, local instability

Acknowledgement

Работа выполнена при поддержке РФФИ р2006_юг (проект 06-01-96641).

Author Info

Aleksandr K. Belyaev

д-р. физ.-мат. наук, заместитель директора по научной работе Института проблем машиноведения РАН

e-mail: belyaev@director.ipme.ru

References

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  4. Belyaev A.K. Dynamics of a buckled drillstring rotating in a curved oil wellbore. In: New Applications of Nonlinear and Chaotic Dynamics in Mechanics, ed. F.C. Moon, Kluwer, Dordrecht. 1999. P. 169-171.
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Downloads

Issue

2008. No. 1

Section

Mechanics

Pages

5-11

Submitted

2008-03-15

Published

2008-03-28

How to Cite

Belyaev A.K. Local instability of rotation of a drill string. Ecological Bulletin of Research Centers of the Black Sea Economic Cooperation, 2008, no. 1, pp. 5-11. (In Russian)

Copyright (c) 2008 Belyaev A.K.

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