SYSTEM AND METHOD FOR MITIGATING STICK-SLIP
First Claim
1. A method of rotating a drill string driven by a drive system using a control system, comprising:
- measuring torque values of the drive system with a torque sensor;
determining a frequency of stick-slip oscillations at the drive system based on the torque values using the control system;
determining an estimated instantaneous rotational speed of the drive system with the control system based on at least the frequency of stick-slip oscillations and a characteristic impedance of the drill string;
adjusting the estimated instantaneous rotational speed based on changes in the torque values to define an adjusted estimated instantaneous rotation speed with the control system;
providing an output signal representing the adjusted estimated instantaneous rotational speed to the drive system; and
controlling rotation of a quill of the drive system based on the output signal.
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Accused Products
Abstract
The present disclosure is directed to systems and methods for rotating a drill string to mitigate stick-slip oscillations. An embodiment includes a method of rotating a drill string driven by a drive system using a control system. The method includes measuring torque values of the drive system with a torque sensor. The method also includes determining a frequency of stick-slip oscillations at the drive system based on the torque values using the control system. The method also includes determining an estimated instantaneous rotational speed of the drive system with the control system based on at least the frequency of stick-slip oscillations and a characteristic impedance of the drill string. The method also includes adjusting the estimated instantaneous rotational speed based on changes in the torque values to define an adjusted estimated instantaneous rotation speed with the control system. The method also includes providing an output signal representing the adjusted estimated instantaneous rotational speed to the drive system. The method also includes controlling rotation of a quill of the drive system based on the output signal.
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Citations
25 Claims
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1. A method of rotating a drill string driven by a drive system using a control system, comprising:
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measuring torque values of the drive system with a torque sensor; determining a frequency of stick-slip oscillations at the drive system based on the torque values using the control system; determining an estimated instantaneous rotational speed of the drive system with the control system based on at least the frequency of stick-slip oscillations and a characteristic impedance of the drill string; adjusting the estimated instantaneous rotational speed based on changes in the torque values to define an adjusted estimated instantaneous rotation speed with the control system; providing an output signal representing the adjusted estimated instantaneous rotational speed to the drive system; and controlling rotation of a quill of the drive system based on the output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for rotating a drill string, comprising:
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a drive system configured to rotate the drill string at variable rotational speeds based on control signals received by the drive system; and a control system configured to transmit the control signals to the drive system, wherein the control system is configured to generate the control signals based on at least a frequency of stick-slip oscillations at the drive system, a characteristic impedance of the drill string, and torque values of the drive system. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A control system, comprising:
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an automation controller including a processor and a memory configured to supply a drive system for rotating a drill string with control signals based on at least a frequency of stick-slip oscillations at the drive system, a characteristic impedance of the drill string, and torque values of the drive system; and a display visualization configured to display at least the frequency of stick-slip oscillations at the drive system, the characteristic impedance of the drill string, and the torque values of the drive system. - View Dependent Claims (23, 24, 25)
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Specification