Determining angular offset between geomagnetic and gravitational fields while drilling wellbore
First Claim
1. A method of operating an apparatus while advancing with rotation in a borehole, the method comprising:
- determining angular position of the apparatus about an axis of the apparatus relative to the borehole during the rotation in the borehole by using angular rate readings from an angular rate sensor of the apparatus;
correcting the determination of the angular position of the apparatus relative to a toolface offset of the apparatus by;
dividing each of the rotations into a plurality of divisions using at least one orthogonal pair of a plurality of toolface sensors of the apparatus;
determining a magnetic toolface of the apparatus during the rotation based on geomagnetic readings from at least one geomagnetic sensor of the toolface sensors of the apparatus in each of the divisions of the rotation relative to the geomagnetic field of reference,determining a gravitational toolface of the apparatus during the rotation based on gravitational readings from at least one gravitational sensor of the toolface sensors of the apparatus in each of the divisions of the rotation relative to the gravitational field of reference, andcalculating the toolface offset of the apparatus as a difference between the magnetic toolface and the gravitational toolface; and
directing the apparatus in the borehole based on the corrected angular position.
8 Assignments
0 Petitions
Accused Products
Abstract
An apparatus is directed relative to geomagnetic and gravitational fields of reference while advancing with rotation in a borehole by determining angular position of the apparatus during the rotation and correcting the angular position of the apparatus relative to an offset of a toolface of the apparatus. To do the correction, a magnetic toolface of the apparatus during the rotation is determined based on geomagnetic readings of the apparatus in each of a plurality of divisions of the rotation relative to the geomagnetic field, and a gravitational toolface of the apparatus during the rotation is determined based on gravitational readings of the apparatus in each of the divisions of the rotation relative to the gravitational field. The offset of the toolface is then calculated as a difference between the magnetic toolface and the gravitational toolface. The corrected angular position can then be used in directing the apparatus.
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Citations
21 Claims
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1. A method of operating an apparatus while advancing with rotation in a borehole, the method comprising:
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determining angular position of the apparatus about an axis of the apparatus relative to the borehole during the rotation in the borehole by using angular rate readings from an angular rate sensor of the apparatus; correcting the determination of the angular position of the apparatus relative to a toolface offset of the apparatus by; dividing each of the rotations into a plurality of divisions using at least one orthogonal pair of a plurality of toolface sensors of the apparatus; determining a magnetic toolface of the apparatus during the rotation based on geomagnetic readings from at least one geomagnetic sensor of the toolface sensors of the apparatus in each of the divisions of the rotation relative to the geomagnetic field of reference, determining a gravitational toolface of the apparatus during the rotation based on gravitational readings from at least one gravitational sensor of the toolface sensors of the apparatus in each of the divisions of the rotation relative to the gravitational field of reference, and calculating the toolface offset of the apparatus as a difference between the magnetic toolface and the gravitational toolface; and directing the apparatus in the borehole based on the corrected angular position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An apparatus advancing with rotation in a borehole, the apparatus comprising:
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at least one sensing element comprising; an angular rate sensor configured to obtain angular rate readings of the apparatus about an axis of the apparatus relative to the borehole during rotation, and a plurality of toolface sensors configured to obtain geomagnetic readings of the apparatus relative to the geomagnetic field during the rotation and configured to obtaining gravitational readings of the apparatus relative to the gravitational field during the rotation; and a control system in operable communication with the at least one sensing element and configured to; use the angular rate readings from the angular rate sensor to determine angular position of the apparatus during the rotation in the borehole; divide each of the rotations into a plurality of divisions using at least one orthogonal pair of the toolface sensors; determine a magnetic toolface of the apparatus during the rotation based on the geomagnetic readings of the apparatus in each of the divisions of the rotation relative to the geomagnetic field; determine a gravitational toolface of the apparatus during the rotation based on the gravitational readings of the apparatus in each of the divisions of the rotation relative to the gravitational field; calculate a toolface offset of the apparatus as a difference between the magnetic toolface and the gravitational toolface; and correct the angular position of the apparatus relative to the calculated toolface offset. - View Dependent Claims (18, 19, 20, 21)
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Specification