An inertial measurement unit and method of operation
AssigneePrecision Mining and Drilling Holdings Pty Ltd
InventorsHayden Scott Thomas WALKER, Peter BULLOCK, David MIITEL
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Abstract
The present invention relates generally to the field of inertial measurement units (IMU's) and their use in downhole applications and particularly to an IMU configured to allow a calculation of bias or drift, an encoder steering assembly and a drilling target indicator to calculate position of a downhole implement relative to an intended path.
Claims20
An inertial measurement unit configured for use with a downhole implement, comprising:
- a primary casing removably and coaxially attached to a guide rod which is locatable within the hollow interior or bore of the downhole implement and can translate along the length of the implement;
- a secondary casing enclosing the primary casing;
- a primary sensor device mounted in the primary casing to measure acceleration and/or angular rate on at least one of an X-axis, Y-axis and Z-axis;
- a secondary sensor device mounted in the secondary casing to measure acceleration and/or angular rate on at least one of an X-axis, Y-axis and Z-axis;
- and
- wherein during an indexing process, the secondary sensor is adapted to be rotatably indexed relative to at least one of the X-axis, Y-axis and Z-axis independently of the primary sensor to thereby provide information regarding bias of the inertial measurement unit on at least one of the X-axis, Y-axis and Z-axis.
A method of determining bias in an inertial measurement unit comprising a primary sensor device and a secondary sensor device comprising the steps of:
- fixing the location and orientation of the primary sensor device;
- indexing the secondary sensor device in a first axis through 90° of rotation relative to the primary sensor device;
- indexing the primary sensor device and secondary sensor device in an axis perpendicular to the first axis through 180° of rotation;
- indexing the secondary sensor device in the first axis though −90° of rotation;
- indexing the primary sensor device and secondary sensor device in the axis perpendicular to the first axis through −180° of rotation;
- calculating the bias of the inertial measurement unit relative to the first axis using the data collected by the primary sensor device and secondary sensor device.
An encoder steering assembly for steering an inertial measurement unit relative to a downhole implement comprising:
- a housing insertable into the hollow bore of the downhole implement;
- an encoder wheel configured to rotate about a first axis;
- a mounting assembly configured to rotate about a second axis;
- a drive to rotate the mounting assembly about the second axis;
- wherein the encoder wheel is mounted in the mounting assembly such that the first axis and the second axis are perpendicular;
- and
- wherein the inertial measurement unit and mounting assembly is mounted in the housing such that the encoder wheel can steer the housing relative to the downhole implement.
A drilling target indicator including a display configured to display an indication of drill tip current position relative to drill tip target position and an angle of deflection required to arrive at the target position from the current position, wherein the angle of deflection determined according to the method including the steps of:
- establishing a collar position of the drill rod associated with the drill tip;
- calculating coordinates to establish the drill tip current position within a hole as drilling is underway;
- and
- calculating an angle of deflection required to arrive at the target position from the current position.
The drilling target indicator of claim 15 wherein the display provides an indication to Clean Copy Docket No.:
- 0116.1111 an operator of any deviation of the drill rod from an intended path.
The drilling target indicator of claim 15 wherein the display provides an indication of a correction required for an off-target drill tip to achieve the intended target position.
An inertial measurement unit including at least one sensor device mounted on an X-axis, Y-axis and Z-axis and at least one secondary sensor device mounted on the X-axis, Y-axis or Z-axis wherein the at least one secondary sensor device is mounted to be rotatably indexed relative to the X-axis, Y-axis or Z-axis independently relative to the at least one sensor device.
A method of increasing the effective rate of rotation at which an inertial measurement unit comprising a sensor and housing operates, comprising the step of:
- rotating the sensor in an opposite direction to a rotation of the housing such that the sensor remains within a functional limit to rate of rotation.
Dependencies are inferred from the claim text.