Bore location system

• US 6,922,056 B2
• Filed: 03/03/2004
• Issued: 07/26/2005
• Est. Priority Date: 09/08/2000
• Status: Expired due to Term

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mizuno, Morio
• Primary Examiner(s): Patidar, Jay
• Assistant Examiner(s): Aurora, Reena
• Application Number:
  US10/792,559
• Publication Number:
  US 20040164740A1
• Time in Patent Office: 510 Days
• Field of Search: 324/326, 324/66, 324/67, 324/226, 324/227, 324/202, 324/225, 324/239, 324/329, 324/345, 175/62, 175/45, 343/718
• 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: E21B 7/046 horizontal drilling drilling with mechanical conveying means E21B7/003
• 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 3/15 specially adapted for use during transport, e.g. by a person, vehicle or boat

Abstract

A system and method for locating a horizontal bore below a ground surface includes a transmitting source configured to radiate from the bore a dipole magnetic field aligned with the bore. A receiver is located remote from the transmitting source and has a first coil and a second coil. Each coil defines an axis, wherein the axes of the first coil and the second coil are orthogonal to each other. A measurement device is in communication with the coils and configured to measure the phase of signals induced on the coils by the magnetic field when the axis of the first coil is horizontally perpendicular to the axis of the magnetic field and the axis of the second coil is vertically perpendicular to the axis of the magnetic field. The measurement device is also configured to determine the lateral position of the transmitting source relative to the coils responsively to the phase of the signals on the first coil and the second coil.

Claims

1. A method for locating a horizontal bore below a ground surface, said method comprising:

radiating a magnetic field from said bore using a transmitting source positioned therein;

arranging a receiver remote from said transmitting source having a plurality of coils disposed so that each one of the coils occupies a predetermined operative position with respect to a horizontal plane when said receiver is disposed in a first position with respect to said horizontal plane and so that at least a first one of the coils moves into said operative position of a second one of said coils when said receiver is rotated to a second position with respect to said horizontal plane, said coils generating a plurality of signals induced on the coils by said magnetic field;

providing a processor for using at least a first signal and a second signal produced by respective first and second ones of said coils induced on the coils by said magnetic field; and

configuring a control circuit for selectively transferring the first and second signals to the processor by detecting one of the first position and the second position of the receiver arrangement and routing the second signal to the processor in place of the first signal when the receiver is in said second receiver position.

2. The method of system as in claim 1 including providing a plurality of said first coils.

3. The method of claim 1 including offsetting said second position of said receiver at least approximately 90°

from said first position of said receiver.

4. The method of claim 1 including using a tilt switch in the control circuit to detect the first and second positions of the receiver.

5. The method of claim 1 including using the control circuit to multiplex the first and second signals from the first and second coils to the processor.

6. The method of claim 5 including configuring said control circuit to include a tilt switch that outputs a signal to said processor that changes state between said first position of said receiver and said second position of said receiver, and controlling multiplexing of the first and second signals responsive to said tilt switch signal so that, when said tilt switch signal is in a first said state, said first signal is directed to a first multiplexer output and said second signal is directed to a second multiplexer output and, when said tilt switch signal is in a second said state, moving said first signal of said first coil to said second multiplexer output to replace said second signal.

7. The method of claim 1 wherein said first coil and said second coil define a first coil axis and a second coil axis respectively and supporting the first coil axis and the second coil axis in an orthogonal relationship.

8. The method of claim 7 including providing a plurality of said first coils as part of said receiver.