Magnetic Beacon Guidance System

• US 20090222208A1
• Filed: 12/29/2005
• Published: 09/03/2009
• Est. Priority Date: 12/29/2005
• Status: Active Grant

• Current Assignee: Neil Speck
• Original Assignee: Neil Speck
• Inventors: Speck, Neil
• Granted Patent: US 8,983,782 B2
• Time in Patent Office: Days
• US Class Current: 702/9
• CPC Class Codes: E21B 47/0228 using electromagnetic energy or detectors therefor
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 7/046 horizontal drilling drilling with mechanical conveying means E21B7/003

Abstract

A method of guiding a probe (20) to a target includes placing a magnetic field generator at the target and guiding the probe (20) to a region of the target. The probe carries a survey sensor pack (28) and the method includes using the survey sensor pack (28), firstly, to obtain a plurality of survey readings and, secondly, to obtain a plurality of magnetic beacon readings using a magnetic field generated by the magnetic field generator. A selected number of the survey readings and the magnetic beacon readings are compared and a difference between the survey readings and the magnetic beacon readings is determined. The method includes compensating for that difference thereafter to guide the probe (20) to the target.

Claims

1. A method of guiding a probe to a target, the method including

placing a magnetic field generator at the target;

guiding the probe to a region of the target, the probe carrying a survey sensor pack;

using the survey sensor pack to obtain a plurality of survey readings;

using the survey sensor pack to obtain a plurality of magnetic beacon readings using a magnetic field generated by the magnetic field generator;

comparing a selected number of the survey readings and the magnetic beacon readings and determining a difference between the survey readings and the magnetic beacon readings; and

compensating for that difference thereafter to guide the probe to the target.

2. The method of claim 1 which includes selecting the magnetic field generator to be of predetermined dimensions.

3. The method of claim 2 which includes selecting the dimensions of the magnetic field generator in dependence of the distance it is estimated the probe is likely to be from the target.

4. The method of claim 1 which includes implementing the magnetic field generator in segments so that a magnetic field generator of desired length can be used.

5. The method of claim 1 which includes initially defining a commencement position and termination position for the probe.

6. The method of claim 1 which includes processing and recording data generated by the probe along its initial trajectory.

7. The method of claim 5 which includes excluding data relating to non-completed, unusable portions of the initial trajectory.

8. The method of claim 1 which includes taking a predetermined number of magnetic beacon readings when the probe is within range of the magnetic field generator.

9. The method of claim 8 which includes deriving fixes from at least two pairs of predetermined magnetic beacon readings.

10. The method of claim 9 which includes selecting each magnetic beacon reading for use in deriving the fixes by comparing the magnetic beacon reading with a corresponding survey reading and, if the magnetic beacon reading differs from the survey reading by an amount exceeding a predetermined value, disregarding that magnetic beacon reading.

11. The method of claim 9 which includes forming a segment of magnetic beacon readings from the fixes.

12. The method of claim 11 which includes comparing the segment of magnetic beacon readings with a segment of corresponding survey readings.

13. The method of claim 8 which includes taking two measurements for each magnetic beacon reading, one with poles of the magnetic field generator in a first orientation and the other with the poles of the magnetic field generator in an opposite orientation to minimise the effects of earth'"'"'s magnetic field.

14. The method of claim 8 which includes obtaining a vector representative of a radial component of the magnetic field generated by the magnetic field generator at each magnetic beacon reading.

15. The method of claim 14 which includes transforming raw vectors from each magnetic beacon reading to obtain the radial component.

16. The method of claim 1 which includes calculating an angular difference between each magnetic beacon reading and its associated survey reading and calculating a difference in displacement between the magnetic beacon reading and its associated survey reading.

17. The method of claim 1 which includes calculating a new trajectory and displaying the new trajectory to an operator.

18. A system for guiding a probe to a target, the system including

a magnetic field generator to be located at the target;

a survey probe to be guided to the target, the survey probe carrying a survey sensor pack, sensors of the sensor pack being operable to obtain a plurality of survey readings and a plurality of magnetic beacon readings using a magnetic field generated by the magnetic field generator; and

processing equipment for processing data relating to a selected number of the measured survey readings and the magnetic beacon readings to determine a difference between the survey readings and the magnetic beacon readings and for compensating for that difference thereafter to guide the probe to the target.

19. The system of claim 18 in which the magnetic field generator has variable dimensions, the dimensions of the magnetic field generator being selected in dependence of the distance it is estimated the probe is likely to be from the target.

20. The system of claim 19 in which the magnetic field generator comprises a plurality of interconnectable segments so that a magnetic field generator of desired length can be used.

21. The system of claim 19 in which the magnetic field generator is a solenoid having switchable poles.

22. The system of claim 18 in which the survey sensor pack comprises a plurality of magnetometer/accelerometer pairs, the pairs being arranged to take the readings along Cartesian coordinates.

23. The system of claim 18 in which the processing equipment is operable to process and record data generated by the probe along its initial trajectory.

24. The system of claim 18 in which the survey pack is operable to take a predetermined number of magnetic beacon readings when the probe is within range of the magnetic field generator.

25. The system of claim 24 in which the processing equipment is operable to derive fixes from at least two pairs of predetermined magnetic beacon readings.

26. The system of claim 25 in which the processing equipment is operable to select each magnetic beacon reading for use in deriving the fixes by comparing the magnetic beacon reading with a corresponding survey reading and, if the magnetic beacon reading differs from the survey reading by an amount exceeding a predetermined value, disregarding that magnetic beacon reading.

27. The system of claim 26 in which the processing equipment is operable to form a segment of magnetic beacon readings from the fixes and to compare the segment of magnetic beacon readings with a segment of corresponding survey readings.

28. The system of claim 18 which includes a switching arrangement for switching the relative orientation of poles of the magnetic field generator to minimize the efforts of earth'"'"'s magnetic field.

29. The system of claim 18 in which the processing equipment is operable to obtain a vector representative of a radial component of the magnetic field generated by the magnetic field generator at each magnetic beacon reading.

30. The system of claim 29 in which the processing equipment is operable to transform raw vectors from each magnetic beacon reading to obtain the radial component.

31. The system of claim 18 in which the processing equipment is operable to calculate an angular difference between each magnetic beacon reading and its associated survey reading and to calculate a difference in displacement between the magnetic beacon reading and its associated survey reading.

32. The system of claim 18 in which the processing equipment is operable to calculate a new trajectory for the probe.

33. The system of claim 32 which includes a display arrangement for displaying the new trajectory of the probe to an operator.