GYROSCOPICALLY-ORIENTED SURVEY TOOL

• US 20090217539A1
• Filed: 10/13/2005
• Published: 09/03/2009
• Est. Priority Date: 12/13/2004
• Status: Active Grant

• Current Assignee: Icefield Tools Corporation
• Original Assignee: Icefield Tools Corporation
• Inventors: Blake, Erik
• Granted Patent: US 7,730,625 B2
• Time in Patent Office: Days
• US Class Current: 33/302
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: G01V 1/46 Data acquisition

Abstract

A gyroscopically-oriented survey tool, includes a housing having an axis. Three accelerometers are mounted in the housing with their axes set orthogonally. A first of the axes is aligned to the axis of the housing. A second of the axes is perpendicular to the first A third of the axes is perpendicular to both of the first and the second. Three gyroscopes are mounted pseudo-orthogonally in the housing with their axes set at relative angles of other than 90 degrees. None of the axes of the gyroscopes are mounted parallel to the axes of the accelerometers. This configuration permits data from the accelerometers to be used to check the quality of data from the gyroscopes.

Claims

1. An apparatus, comprising:

a housing having an axis;

three accelerometers mounted in the housing with their axes set orthogonally, a first of the axes being aligned to the axis of the housing, a second of the axes being perpendicular to the first, and a third of the axes being perpendicular to both of the first and the second; and

three gyroscopes mounted pseudo-orthogonally in the housing with their axes set at relative angles of other than 90 degrees, none of the axes of the gyroscopes being mounted parallel to the axes of the accelerometers.

2. The apparatus as defined in claim 1, wherein means are provided for recording and/or integrating data from the accelerometers and data from the gyroscopes.

3. The apparatus as defined in claim 1, wherein there is provided three magnetic field sensors or magnetic flux sensors mounted in the housing with their axes set orthogonally to serve as a magnetometer.

4. The apparatus as defined in claim 3, wherein the axes of the magnetometer are aligned with the axes of the accelerometers.

5. The apparatus as defined in claim 1, wherein means are provided for using corroborating data from the accelerometers to correct the offset and scale factors of the gyroscopes.

6. The apparatus as defined in claim 3, wherein means are provided for computing apparatus azimuth using accelerometer and magnetometer data and using such apparatus azimuth to correct gyroscope offset and scale factors.

7. The apparatus as defined in claim 5, wherein means are provided for determining the quality of the derived apparatus orientation by assessing the degree to which gyroscope offset and scale factors are constrained.

9. The method as defined in claim 1, wherein the gyroscopically-oriented survey tool includes three magnetic field sensors or magnetic flux sensors mounted in the housing with their axes set orthogonally to serve as a magnetometer and including a step of computing apparatus azimuth using accelerometer and magnetometer data and using such apparatus azimuth to correct gyroscope offset and scale factors.

10. The method as defined in claim 9, wherein the axes of the magnetometer are aligned with the axes of the accelerometers.

11. The method as defined in claim 9, including a step of determining the quality of the derived apparatus orientation by assessing the degree to which gyroscope offset and scale factors are constrained.

8. A method, comprising the steps of:

providing a gyroscopically-oriented survey tool which includes;

a housing having an axis;

three accelerometers mounted in the housing with their axes set orthogonally, a first of the axes being aligned to the axis of the housing, a second of the axes being perpendicular to the first, and a third of the axes being perpendicular to both of the first and the second;

three gyroscopes mounted pseudo-orthogonally in the housing with their axes set at relative angles of other than 90 degrees, none of the axes of the gyroscopes being mounted parallel to the axes of the accelerometers; and

using corroborating data from the accelerometers to correct the offset and scale factors of the gyroscopes.