Method and apparatus for determining drill string movement mode
First Claim
1. A method for determining a mode of movement in a drill string, comprising:
- measuring lateral acceleration of the drill string;
determining a lateral position of the drill string with respect to time from the acceleration measurements; and
determining the mode from the position with respect to time.
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Abstract
A method for determining movement mode in a drill string includes measuring lateral acceleration of the drill string, determining lateral position of the drill string from the acceleration measurements, and determining mode from the position with respect to time. Another method includes measuring drill string acceleration along at least one direction, spectrally analyzing the acceleration, and determining existence of a particular mode from the spectral analysis. A method for determining destructive torque on a BHA includes measuring angular acceleration at at least one location along the BHA, and comparing the acceleration to a selected threshold. The threshold relates to a moment of inertia of components of the BHA and a maximum torque applicable to threaded connections between BHA components. A warning is generated when acceleration exceeds the threshold.
24 Citations
32 Claims
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1. A method for determining a mode of movement in a drill string, comprising:
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measuring lateral acceleration of the drill string; determining a lateral position of the drill string with respect to time from the acceleration measurements; and determining the mode from the position with respect to time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for determining a mode of motion of a drill string, comprising:
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measuring a parameter related to acceleration of the drill string along at least one direction; spectrally analyzing the measurements of acceleration; and determining existence of a particular mode from the spectrally analyzed measurements, wherein the determining the particular mode comprises identifying a component frequency in the spectrally analyzed measurements which corresponds to at least one of a resonant frequency and a whirl frequency of a selected component of the drill string. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for estimating wear on a drill string, comprising:
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determining a mode of motion of the drill string; calculating side forces generated by contact between affected components of the drill string and a wall of a wellbore as a result of the mode of motion; and estimating a wear rate corresponding to the side forces and a rate of rotation of the drill string. - View Dependent Claims (20)
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21. A method for estimating fatigue on a drill string, comprising:
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determining a mode of motion of the drill string; calculating flexural forces generated as a result of the mode of motion; and estimating a fatigue rate from the flexural forces. - View Dependent Claims (22)
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23. An apparatus for determining mode of movement in a drill string, comprising:
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a sensor for measuring lateral acceleration of the drill string; means for determining a lateral position of the drill string with respect to time from the acceleration measurements; and means for determining the mode from the position with respect to time. - View Dependent Claims (24, 25, 26, 27, 28)
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29. A apparatus for determining a mode of motion of a drill string, comprising:
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a sensor for measuring a parameter related to acceleration of the drill string along at least one direction; a spectral analyzer operatively coupled to the sensor; and means for determining existence of a particular mode from the spectrally analyzed measurements the means for determining the particular mode comprising means for identifying a component frequency operatively coupled to the spectral analyzer, the component frequency corresponds to at least one of whirl rate, torsional resonance, axial resonance and lateral resonance of the selected component of the drill string. - View Dependent Claims (30, 31, 32)
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Specification