Dipole locator using multiple measurement points

• US 8,497,684 B2
• Filed: 07/28/2010
• Issued: 07/30/2013
• 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.
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US12/844,886
• Publication Number:
  US 20100289496A1
• Time in Patent Office: 1,098 Days
• Field of Search: 324326-327, 324338-339
• US Class Current: 324/326
• 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 method for tracking a below ground source of a dipole magnetic field, the method comprising:

simultaneously detecting in three dimensions the dipole magnetic field from the below ground source at each of at least two horizontally disposed distinct points of a receiver frame; and

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

2. The method of claim 1 further comprising the step of displaying the location of the below ground source relative to the receiver frame.

3. The method of claim 1 further comprising the step of determining the distance between the below ground source and the receiver frame.

4. The method of claim 1 further comprising the steps of:

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

calculating the depth of the below ground source of the dipole magnetic field.

5. The method of claim 1 further comprising the steps of:

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

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

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

6. The method of claim 5 wherein the step of locating a point where the detected dipole magnetic field is the same at each of the three distinct points is accomplished by measuring the total field amplitudes of the detected signals.

7. The method of claim 6 further comprising the step of rotating the receiver frame to an alignment consistent with an axis of the below ground source of the dipole magnetic field.

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

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

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

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.

9. The method of claim 8 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.