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Vibration Analysis of Drill String under Inclined Drilling Including Stick-Slip Phenomenon

Damshenas, Mohammad | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 46459 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Ahmadiyan, Mohammad Taghi
  7. Abstract:
  8. Vibration is one of the most important factors in design, operation and lifetime of drill string. Evaluation of vibration in the drill string like other rotating machines is very important and according to the length of drill string, whirling is one of the issues discussed. The aim of this thesis is non-linear analysis of the oblique long drill string. By considering the effects of passing drill mud around drill as well as properties of the drilling mud and stick - slip effect in creating whirling. Therefore, the equations related to kinetic and potential energy of a rotating drill string by taking longitudinal and transverse vibrations are written and by using the Lagrange method, equations of motion are obtained.
    In this modeling the effect of drill string weight and stick-slip phenomenon from bottom well is considered. The effects of drilling mud on the results and experimental relationships of Paidoussis are modeled and the finite element method is used to solve the equations.
    Finally by non-linear method due to the non-linear terms in the equations and also momentum changes due to stick -slip phenomenon and stabilizers order are used. The results show significant importance of the nonlinear terms on the natural frequency and time response.
    The results show that increasing the flow of drilling mud will reduce the natural frequency and vibration amplitude. Also, from the beginning of movement drill string, stick-slip effect is on longitudinal vibrations and then starts influence on transverse vibration.
  9. Keywords:
  10. Drill String ; Angular Velocity ; Weight on Bit ; Slurries

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