Identification and mitigation of whirl within a drilling system
AssigneeSchlumberger Technology Corporation
InventorsAshley Bernard Johnson, Spyridon Joseph Kotsonis, Ross Lowdon
Life of this patent
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Abstract
Whirl in a drilling system may be identified and mitigated by monitoring signals from a plurality of sensors positioned at various axial locations along a drill string of the drilling system, determining a respective frequency component and a respective amplitude component for each of the signals, identifying whirl in the drill string based on at least two of the respective frequency components and their respective amplitude components, and mitigating the whirl by introducing noise into the drilling system to reduce or eliminate the whirl without removing the drill string from a bottom of a borehole and without terminating all rotation of the drill string.
Claims18
A system, comprising:
- a plurality of sensors placed at various axial positions on a drill string and configured to output respective sensor signals indicative of movement of the drill string;
- and
- at least one controller communicatively coupled to the plurality of sensors, wherein the at least one controller is configured to:
- a) identify whirl in the drill string by operations that include
- i) determining frequency components and corresponding amplitude components for the sensor signals;
- ii) comparing a first frequency component of the frequency components of i) to a second frequency component of the frequency components of i), wherein the first and second frequency components are based on the sensor signals produced by the plurality of sensors at different axial positions on the drill string;
- iii) determining if a frequency difference between the first frequency component and the second frequency component of ii) exceeds a frequency threshold;
- iv) if the frequency difference between the first frequency component and the second frequency component is determined to exceed the frequency threshold in iii), comparing both a first amplitude component of the amplitude components of i) and a second amplitude component of the amplitude components of i) to an amplitude threshold, wherein the first amplitude component corresponds to the first frequency component of ii) and the second amplitude component corresponds to the second frequency component of ii);
- and
- v) identifying whirl in the drill string if both the first and second amplitude components exceed the amplitude threshold of iv);
- and
- b) control a downhole component, a surface component, or a combination thereof, in response to identifying the whirl, to introduce noise into the drill string to mitigate the whirl without removing the drill string from a bottom of a borehole and without terminating all rotation of the drill string.
A method of identifying and mitigating whirl within a drilling system, the method comprising:
- a) monitoring sensor signals from a plurality of sensors positioned at various axial locations along a drill string of the drilling system;
- b) determining frequency components and corresponding amplitude components for the sensor signals;
- c) identifying whirl in the drill string by operations that include
- i) comparing a first frequency component of the frequency components of b) to a second frequency component of the frequency components of b), wherein the first and second frequency components are based on the sensor signals produced by the plurality of sensors at different axial positions on the drill string;
- ii) determining if a frequency difference between the first frequency component and the second frequency component of i) exceeds a frequency threshold;
- iii) if the frequency difference between the first frequency component and the second frequency component is determined to exceed the frequency threshold in ii), comparing both a first amplitude component of the amplitude components of b) and a second amplitude component of the amplitude components of b) to an amplitude threshold, wherein the first amplitude component corresponds to the first frequency component of i) and the second amplitude component corresponds to the second frequency component of i);
- and
- iv) identifying whirl in the drill string if both the first and second amplitude components exceed the amplitude threshold of iii);
- and
- d) mitigating the whirl by introducing noise into the drilling system to reduce or eliminate the whirl without removing the drill string from a bottom of a borehole and without terminating all rotation of the drill string.
Dependencies are inferred from the claim text.