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Analysis and Design of an Observer and Robust Controller to Reduce Undesired Coupled Axial-Torsional Vibrations in A Horizontal Drill String

Barjini، Amir Hossein | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56810 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Moradi, Hamed
  7. Abstract:
  8. Nowadays, horizontal drill string is a powerful tool for drilling in the oil and gas industry and an efficient method for constructing underground tunnels in cities. Despite its many uses, this method is exclusive to limited countries and is considered among the most advanced methods for drilling. One of the most important problems in the field of horizontal drilling is the existence of destructive axial, torsional and lateral vibrations. If these vibrations are not controlled, they can cause irreparable damage to the plant and drilling well. Among the introduced vibrations, axial and torsional vibrations have a very dominant effect on the drilling process, so the purpose of this research is to control the coupled axial-torsional vibrations of the horizontal drill string. In this thesis, in the first step, the horizontal drill string system is introduced by presenting a brief history and introducing its advantages and disadvantages. In the following, the components of the system are introduced. Then important articles in this field are introduced and their strengths and weaknesses are analyzed. Modeling and extraction of the coupled axial-torsional equations are done in the next chapter and by numerically solving the equations, axial and torsional vibration modes are extracted. Using the mode summation method, it is shown that the use of three vibration modes for axial motion and three vibration modes for torsional motion is appropriate and the error is less than 0.1% for axial motion and less than 0.02% for torsional motion to the system. In the following, for the first time, a non-linear sliding mode controller has been designed for the system. Since access to all the state variables is necessary for designing the controller, for the first time, a nonlinear state observer system, as an Extended Kalman filter, has been designed for this set. The comparative analysis of the proposed controller and observer with two other controllers shows that the proposed controller has a response with less settling time, no overshoot and no vibration
  9. Keywords:
  10. Drill String ; Nonlinear Dynamics ; Horizontal Drilling ; Coupled Axial Torsional Vibrations ; Mode-Summation Method ; Sliding Mode Controller ; Stability ; Extended Kalman Filter

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