Flux orientation locating in a drilling system

• US 6,693,429 B2
• Filed: 06/02/2003
• Issued: 02/17/2004
• Est. Priority Date: 03/01/1991
• Status: Expired due to Fees

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US10/453,375
• Publication Number:
  US 20030208318A1
• Time in Patent Office: 260 Days
• Field of Search: 324/326, 324/327, 324/328, 324/329, 175/45
• US Class Current: 324/326
• CPC Class Codes: E21B 47/0228 using electromagnetic energy or detectors therefor
• 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: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/20 the indication being based on the inclination of the surface of a liquid relative to its container
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• 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
• 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

Abstract

An above ground locator includes an apparatus for determining the strength of the locating signal at a selected point relative to the boring tool. The apparatus includes an antenna arrangement configured for measuring the strength of the locating signal at the selected point along first and second orthogonally opposed receiving axes to produce first and second received signals. A phase shifting arrangement phase shifts the first and second received signals in a predetermined way to generate first and second phase shifted signals, respectively. Thereafter, a summing arrangement adds the first and second phase shifted received signals to generate an output signal which is a vector sum of the first and second received signals. In one feature, third and fourth signals derived from the first and second signals are used to eliminate balance point ambiguity which is present using the first and second signals alone. In another feature, signals corresponding to first, second, third and fourth axes are compared in a way which confines the possible locations of an above ground point to one particular type of region out of a plurality of different types of regions. Tracking of the boring tool may be accomplished in a number of described ways since the regions occur in a specific sequence along the intended path with respect to the location of the boring tool.

Claims

1. In a system for tracking a boring tool within an underground region in which the boring tool is configured for transmitting a locating signal while moving along an intended path for receipt by a locator such that locating signal flux surrounds the intended path and a portion of the flux is vertically oriented to define a forward locate point ahead of the boring tool and a rear locate point behind the boring tool, the improvement comprising the steps of:

a) positioning the locator at an arbitrary above ground point with respect to the intended path;

b) measuring a directional orientation of the locating signal flux at the arbitrary above ground point using the locator;

c) based at least in part on the measured directional orientation;

providing an initial indication in a direction toward at least one of the locate points;

d) moving the locator in the indicated initial direction while continuing to monitor the directional orientation of the locating signal flux; and

e) indicating the arrival of the locator at the indicated locate point when the locating signal flux is vertically oriented.

2. The improvement of claim 1 further comprising the steps of:

f) moving the locator from the indicated locate point while monitoring the signal strength of the locating signal flux at the locator in a way which establishes whether the indicated locate point is the forward or rear locate point.

3. The improvement of claim 1 further comprising the steps of:

f) measuring the signal strength of the locating signal flux at the indicated locate point and storing the measured signal strength as a reference value;

g) moving the locator from the indicated locate point while monitoring signal strength of the locating signal flux; and

h) comparing the monitored signal strength during said movement with the reference value in a way which establishes whether the indicated locate point is the forward or rear locate point.

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

f) after having found the indicated locate point, providing one or more additional indications using certain characteristics of the locating signal, which additional indications point out the direction of an overhead point substantially above the boring tool.

5. The improvement of claim 4 wherein the additional indications are in an opposite direction with respect to the initial indication.

6. The improvement of claim 4 wherein the additional indications are in substantially the same direction with respect to the initial indication.

7. The improvement of claim 4 wherein said certain characteristics include the signal strength of the locating signal.