Methods and systems for determining angular orientation of a drill string
First Claim
Patent Images
1. A method, comprising:
- causing a drill string to rotate within an earthen formation;
monitoring the magnetic field of the earthed formation as the drill string rotates;
generating an electrical signal in response to a periodically-varying characteristic of the magnetic field;
sending the electrical signal to a component of the drill string that is responsive to the electrical signal;
determining gravity tool face and magnetic tool face of the component of the drill while the component of the drill string is not rotating;
calculating a difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating;
calculating a first angular position of the component corresponding to a difference between an angular position at which an action of the component of the drill string will be initiated, and the difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating; and
timing the generation of the electrical signal based on the difference between the angular position at which a response of the component of the drill string will be initiated, and the difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating.
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Abstract
Preferred methods and systems generate a control input based on a periodically-varying characteristic associated with the rotation of a drill string. The periodically varying characteristic can be correlated with the magnetic tool face and gravity tool face of a rotating component of the drill string, so that the control input can be used to initiate a response in the rotating component as a function of gravity tool face.
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Citations
36 Claims
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1. A method, comprising:
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causing a drill string to rotate within an earthen formation; monitoring the magnetic field of the earthed formation as the drill string rotates; generating an electrical signal in response to a periodically-varying characteristic of the magnetic field; sending the electrical signal to a component of the drill string that is responsive to the electrical signal; determining gravity tool face and magnetic tool face of the component of the drill while the component of the drill string is not rotating; calculating a difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating; calculating a first angular position of the component corresponding to a difference between an angular position at which an action of the component of the drill string will be initiated, and the difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating; and timing the generation of the electrical signal based on the difference between the angular position at which a response of the component of the drill string will be initiated, and the difference between the gravity tool face and magnetic tool face determined while the component of the drill string is not rotating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method, comprising:
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drilling a subsurface bore using a rotating drill string; calculating a time required for a rotating component of the drill string to rotate through an angular displacement approximately equal to an angular distance between a first angular position of the rotating component, and a second angular position of the rotating component at which a predetermined action of the rotating component will be initiated; determining when the rotating component reaches the first angular position by measuring a quantity that varies with the angular position of the rotating component; and monitoring the time that elapses after the rotating component reaches the first angular position until at least the time that it reaches approximately the second angular position. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method, comprising:
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drilling a subsurface bore using a rotating drill string; calculating a time required for a rotating component of the drill string to rotate through an angular displacement approximately equal to an angular distance between a first angular position of the rotating component, and a second angular position of the rotating component at which a predetermined action of the rotating component will be initiated; determining when the rotating component reaches the first angular position by measuring a quantity that varies with the angular position of the rotating component, wherein the quantity that varies with the rotation of the rotating component varies periodically with the rotation of the drill string; monitoring the time that elapses after the rotating component reaches the first angular position until at least the time that it reaches approximately the second angular position; determining gravity tool face and magnetic tool face of the component while the rotating component is not rotating; calculating a difference between the gravity tool face and magnetic tool face determined while the rotating component is not rotating; and determining the second angular position by calculating a difference between an angular position at which a response of the rotating component is to be initiated, and the difference between the gravity tool face and magnetic tool face determined while the rotating component is not rotating. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A method, comprising:
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determining gravity tool face and apparent magnetic tool face of a rotatable component while the rotatable component is not rotating; determining an offset between the gravity tool face and the apparent magnetic tool face; determining a first angular position by calculating a difference between the offset and an angular position at which a desired action of the rotatable component is to be initiated; measuring a component of a geomagnetic field around the rotatable component while the rotatable component is rotating; calculating an angular distance between the first angular position and a second angular position at which a measured value of the geomagnetic field is approximately zero; and calculating a time required for the rotatable component to rotate from the second angular position to the first angular position. - View Dependent Claims (32, 33)
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34. A system, comprising:
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at least two accelerometers that measure components of a gravitational field around a rotatable component of a drill string; a two or three-axis magnetometer that measures components of a magnetic field around the rotatable component; a first controller communicatively coupled to the accelerometers and the magnetometer, wherein the controller generates an electrical signal in response to a periodically-varying characteristic of the magnetic field, and sends the electrical signal to a component of the drill string that is responsive to the electrical signal; and a second controller communicatively coupled to the accelerometers, and a telemetry system that communicatively couples the first and second controllers, the second controller mounted up hole of the telemetry system, wherein the first controller determines gravity tool face and magnetic tool face of the component while the component is not rotating;
calculates a difference between the gravity tool face and magnetic tool face determined while the component is not rotating; and
calculates a first angular position corresponding to a difference between an angular position at which an action of the component will be initiated, and the difference between the gravity tool face and magnetic tool face determined while the component is not rotating. - View Dependent Claims (35, 36)
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Specification