Dipole Locator Using Multiple Measurement Points

• US 20100289496A1
• Filed: 07/28/2010
• Published: 11/18/2010
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Charles Machine Works Incorporated The
• Original Assignee: Charles Machine Works Incorporated The
• Inventors: Cole, Scott B., Gard, Michael F., Brown, David R., Marshall, Bradley S.
• Granted Patent: US 8,497,684 B2
• Time in Patent Office: Days
• US Class Current: 324/343
• CPC Class Codes: E21B 47/0232 at least one of the energy sources or one of the detectors being located on or above the ground surface
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00
• CPC Class Codes: G01V 3/165 operating with magnetic or electric fields produced or modified by the object or by the detecting device with electromagnetic waves G01V3/17
• CPC Class Codes: H01Q 1/04 Adaptation for subterranean or subaqueous use
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

A receiver and tracking system for identifying a location of a magnetic field source. In a preferred embodiment a plurality of tri-axial antennas are positioned at three distinct points on a receiver frame. Each antenna detects a magnetic field from a source and a processor is used to determine a location of the source relative to the frame using the antenna signals. Each tri-axial antenna comprises three windings in each of three channels defined by a support structure. The windings each define an aperture area. The windings have substantially identical aperture areas and have a common center point. The receiver may to display to the operator the relative location of the field source or may direct the operator to a spot directly above the field source.

Claims

1. A receiver system for identifying a location of a magnetic field source, the receiver system comprising:

a frame;

a first antenna assembly supported by the frame and adapted to detect a magnetic field from a source;

a second antenna assembly supported by the frame and adapted to detect the magnetic field from the source; and

a processor adapted to receive an antenna signal from each of the antenna assemblies and to determine a location of the source relative to the frame using the antenna signals.

2. The receiver system of claim 1 further comprising a third antenna assembly supported by the frame and adapted to detect the magnetic field from the source.

3. The receiver system of claim 2 further comprising:

an orientation sensor adapted to sense an orientation of an antenna plane formed by the antenna assemblies; and

wherein the processor is adapted to determine the location of the source using the antenna signals and the orientation of the antenna plane.

4. The receiver system of claim 3 wherein the orientation sensor is an accelerometer.

5. The receiver system of claim 3 wherein the processor determines the location of the source by using the orientation of the antenna plane to adjust for an effect of pitch on the antenna assemblies.

6. The receiver system of claim 1 wherein the antenna assemblies comprise triaxial antennas.

7. The receiver system of claim 2 wherein the antenna assemblies comprise triaxial antennas.

8. The receiver of claim 6 wherein each of the triaxial antennas comprise circuit boards.

9. The receiver system of claim 6 wherein each of the triaxial antennas comprises:

a first winding defining an aperture area;

a second winding defining an aperture area; and

a third winding defining an aperture area.

10. The receiver system of claim 9 wherein the aperture area of each winding is the same;

and wherein the windings have a common centerpoint.

11. The receiver system of claim 9 wherein each winding comprises approximately 100 turns.

12. The receiver system of claim 2 further comprising a fourth antenna assembly.

13. The receiver system of claim 2 wherein each of the antenna assemblies is positioned at a vertex of an equilateral triangle.

14. The receiver system of claim 13 wherein a center point of each of the antenna assemblies define a vertex of the equilateral triangle.

15. The receiver system of claim 13 wherein the antenna assemblies are approximately 18 inches apart.

16. The receiver system of claim 1 wherein the processor determines the location of the source relative to the frame by identifying an x-y-z coordinate position of the frame with the source as the origin of the x-y-z coordinate system.

17. The receiver system of claim 16 wherein the processor determines the location of the source relative to the frame by further identifying a rotation value to align the frame with the source.

18. A method for tracking a below ground source of a magnetic field, the method comprising:

simultaneously detecting in three dimensions a magnetic field from a source at each of at least two distinct points of a receiver frame; and

determining a location of the source relative to the receiver frame using the detected field values.

19. The method of claim 18 further comprising the step of displaying the location of the source relative to the receiver.

20. The method of claim 18 further comprising the step of determining the distance between the source and the receiver frame.

21. The method of claim 18 further comprising the steps of:

moving the receiver frame to a point directly above the source of the magnetic field; and

calculating the depth of the source of the magnetic field.

22. The method of claim 18 further comprising the steps of:

simultaneously detecting in three dimensions the magnetic field from the source at a third distinct point of the receiver frame;

locating a point where the detected magnetic field is the same at each of the three distinct points; and

moving the receiver frame to a point directly above the source of the magnetic field.

23. The method of claim 22 wherein the step of locating a point where the detected magnetic field is the same at each of the three distinct points is accomplished by measuring the total field amplitudes of the detected signals.

24. The method of claim 23 further comprising the step of rotating the receiver frame to an alignment consistent with an axis of the source of the magnetic field.

25. The method of claim 18 further comprising:

placing the receiver assembly on the ground in a proximity of a drill bit;

aligning the receiver with a desired bore path;

advancing the drill bit forward without rotation to perform a steering correction in the horizontal plane;

transmitting an orientation of the drill bit relative to the receiver from the receiver to an operator; and

transmitting a distance of forward advance of the drill bit without rotation from the receiver to the operator.

26. The method of claim 25 wherein the step of transmitting an orientation or transmitting a distance comprises:

alternately turning a transmitter on and off to communicate data in binary form;

detecting a signal condition when the transmitter is on and a no signal condition when the transmitter is off; and

decoding data communicated from a series of signal conditions and no signal conditions.

27. A horizontal directional drilling system comprising:

a drilling machine;

a drill string operatively connected to the drilling machine;

a downhole tool assembly supported at a downhole end of the drill string, the downhole tool assembly comprising a magnetic field transmitter; and

a receiver assembly comprising;

a frame;

at least a first antenna assembly and a second antenna assembly both supported by the frame and adapted to detect a magnetic field from the magnetic field transmitter; and

a processor adapted to receive an antenna signal from each of the antenna assemblies and to determine a location of the magnetic field transmitter relative to the frame using the antenna signals.

28. The horizontal directional drilling system of claim 27 wherein the receiver assembly further comprises a third antenna assembly supported by the frame and adapted to detect the magnetic field from the magnetic field transmitter.

29. The horizontal directional drilling system of claim 28 wherein the receiver assembly further comprises:

an orientation sensor adapted to sense an orientation of an antenna plane formed by the antenna assemblies; and

wherein the processor is adapted to determine the location of the magnetic field transmitter using the antenna signals and the orientation of the antenna plane.

30. The horizontal directional drilling system of claim 29 wherein the orientation sensor is an accelerometer.

31. The horizontal directional drilling system of claim 29 wherein the processor determines the location of the magnetic field transmitter by using the orientation of the antenna plane to adjust for an effect of pitch on the antenna assemblies.

32. The horizontal directional drilling system of claim 27 wherein the antenna assemblies comprise triaxial antennas.

33. The horizontal directional drilling system of claim 28 wherein the antenna assemblies comprise triaxial antennas.

34. The horizontal directional drilling of claim 33 wherein each of the triaxial antennas comprise circuit boards.

35. The horizontal directional drilling system of claim 28 wherein each of the triaxial antennas comprises:

a first winding defining an aperture area;

a second winding defining an aperture area; and

a third winding defining an aperture area.

36. The horizontal directional drilling system of claim 35 wherein the aperture area of each winding is the same;

and wherein the windings have a common centerpoint.

37. The horizontal directional drilling system of claim 35 wherein each winding comprises approximately 100 turns.

38. The horizontal directional drilling system of claim 28 wherein the receiver assembly further comprises a fourth antenna assembly.

39. The horizontal directional drilling system of claim 28 wherein each of the antenna assemblies is positioned at a vertex of an equilateral triangle.

40. The horizontal directional drilling system of claim 39 wherein a center point of each of the antenna assemblies define a vertex of the equilateral triangle.

41. A method for drilling a horizontal borehole, the method comprising:

placing a receiver assembly, comprising a plurality of antenna assemblies, on the ground in a proximity of a drill bit, wherein each antenna assembly comprises triaxial antennas;

aligning the receiver assembly with a desired bore path;

advancing the drill bit forward without rotation to perform a steering correction in the horizontal plane;

transmitting an orientation of the drill bit relative to the receiver assembly from the receiver assembly to an operator; and

transmitting a distance of forward advance of the drill bit without rotation from the receiver assembly to the operator.