System and method for using microgyros to measure the orientation of a survey tool within a borehole
First Claim
1. A survey tool for determining an orientation of the survey tool within a borehole, the survey tool comprising:
- a plurality of rotation sensors, each rotation sensor having a sensing axis and a direction of least acceleration sensitivity, each rotation sensor adapted to generate a first signal indicative of a detected angular rotation rate about its sensing axis, the plurality of rotation sensors mounted in a housing with their sensing axes generally parallel to one another and with their directions of least acceleration sensitivity generally non-parallel to one another;
a plurality of acceleration sensors mounted in the housing, each acceleration sensor having a sensing direction, each acceleration sensor adapted to generate a second signal indicative of detected acceleration along its sensing direction; and
a controller adapted to receive a first signal from each of the plurality of rotation sensors and a second signal from each of the plurality of acceleration sensors, the controller adapted to calculate a weighted average of the detected angular rotation rates from the plurality of rotation sensors, the weighted average including the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity.
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Abstract
A system and method for determining an orientation of the survey tool within a borehole utilizes a survey tool including a plurality of rotation sensors each having a sensing axis and a direction of least acceleration sensitivity. The plurality of rotation sensors are mounted in a housing with their sensing axes generally parallel to one another and with their directions of least acceleration sensitivity generally non-parallel to one another. The survey tool further includes a controller adapted to calculate a weighted average of the detected angular rotation rates from the plurality of rotation sensors. The weighted average includes the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity.
77 Citations
38 Claims
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1. A survey tool for determining an orientation of the survey tool within a borehole, the survey tool comprising:
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a plurality of rotation sensors, each rotation sensor having a sensing axis and a direction of least acceleration sensitivity, each rotation sensor adapted to generate a first signal indicative of a detected angular rotation rate about its sensing axis, the plurality of rotation sensors mounted in a housing with their sensing axes generally parallel to one another and with their directions of least acceleration sensitivity generally non-parallel to one another;
a plurality of acceleration sensors mounted in the housing, each acceleration sensor having a sensing direction, each acceleration sensor adapted to generate a second signal indicative of detected acceleration along its sensing direction; and
a controller adapted to receive a first signal from each of the plurality of rotation sensors and a second signal from each of the plurality of acceleration sensors, the controller adapted to calculate a weighted average of the detected angular rotation rates from the plurality of rotation sensors, the weighted average including the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A control system of a rotatably steerable drilling system configured to drill in a selected drilling direction of a plurality of drilling directions, the control system configured to adjust the selected drilling direction, the control system comprising:
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a plurality of rotation sensors, each rotation sensor having a sensing axis and a direction of least acceleration sensitivity, each rotation sensor adapted to generate a first signal indicative of a detected angular rotation rate about its sensing axis, the plurality of rotation sensors mounted in a housing with their sensing axes generally parallel to one another and with their directions of least acceleration sensitivity generally non-parallel to one another;
a plurality of acceleration sensors mounted in the housing, each acceleration sensor having a sensing direction, each acceleration sensor adapted to generate a second signal indicative of detected acceleration along its sensing direction; and
a controller adapted to receive a first signal from each of the plurality of rotation sensors and a second signal from each of the plurality of acceleration sensors, the controller adapted to calculate a weighted average of the detected angular rotation rates from the plurality of rotation sensors, the weighted average including the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity.
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25. A method of determining an orientation of a survey tool within a borehole, the method comprising:
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providing a plurality of rotation sensors, each rotation sensor having a sensing axis and a direction of least acceleration sensitivity, the plurality of rotation sensors having their sensing axes generally parallel to one another and their directions of least acceleration sensitivity generally non-parallel to one another;
obtaining a detected angular rotation rate from each rotation sensor, each detected angular rotation rate being about the sensing axis of the corresponding rotation sensor;
obtaining a detected acceleration along the directions of least acceleration sensitivity of each of the rotation sensors; and
calculating a weighted average of the detected angular rotation rates from the plurality of rotation sensors, the weighted average including the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A rotatably steerable drilling system comprising:
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a drill string configured to drill in a selected direction of a plurality of directions, the drill string comprising a drill bit;
a survey tool in proximity to the drill bit, the survey tool comprising;
a plurality of rotation sensors, each rotation sensor having a sensing axis and a direction of least acceleration sensitivity, each rotation sensor adapted to generate a first signal indicative of a detected angular rotation rate about its sensing axis, the plurality of rotation sensors mounted in a housing with their sensing axes generally parallel to one another and with their directions of least acceleration sensitivity generally non-parallel to one another;
a plurality of acceleration sensors mounted in the housing, each acceleration sensor having a sensing direction, each acceleration sensor adapted to generate a second signal indicative of detected acceleration along its sensing direction; and
a controller configured to receive a first signal from each of the plurality of rotation sensors and a second signal from each of the plurality of acceleration sensors, the controller configured to calculate a weighted average of the detected angular rotation rates from the plurality of rotation sensors, the weighted average including the detected angular rotation rate of each rotation sensor about its sensing axis weighted by the detected acceleration along its direction of least acceleration sensitivity, the controller further configured to generate a third signal indicative of the weighted average; and
a steering mechanism configured to adjust the selected direction in response to the third signal from the controller.
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Specification