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 earth formation;
monitoring a magnetic field as the drill string rotates;
generating an electrical signal in response to a periodically-varying characteristic of the magnetic field; and
sending the electrical signal to a component of the drill string that is responsive to the electrical signal.
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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
47 Claims
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1. A method, comprising:
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causing a drill string to rotate within an earth formation;
monitoring a magnetic field as the drill string rotates;
generating an electrical signal in response to a periodically-varying characteristic of the magnetic field; and
sending the electrical signal to a component of the drill string that is responsive to the electrical signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. 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 response of the rotating component is occur;
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. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. 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 take place;
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 (35, 36)
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37. 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; and
a controller communicatively coupled to the accelerometer 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. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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Specification