Flux plane locating in an underground drilling system

• US 20030052683A1
• Filed: 10/30/2002
• Published: 03/20/2003
• Est. Priority Date: 08/17/2000
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Brune, Guenter W., Chau, Albert W.
• Granted Patent: US 6,653,837 B2
• Time in Patent Office: Days
• US Class Current: 324/326
• CPC Class Codes: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: G01C 9/02 Details
• 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 3/15 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
• CPC Class Codes: G01V 3/28 using induction coils

Abstract

A portable locator and method are described for tracking the position of a boring tool and/or one or more buried lines within a region. In tracking a boring tool, a flux plane may be used to establish a flux vector as at least an intermediate step in guiding an operator of the portable locator to one or both locate points seen in the boring tool dipole locating field. The horizontal flux vector is used in determining a predicted locate point position. Locating of a locate line in the dipole locating field is performed by determining a predicted locate line angular orientation that is based upon horizontal flux vector determinations. The predicted locate line angular orientation, at least to an approximation, limits the possible directions to and orientations of a predicted locate line relative to the particular orientation of the portable locator at the above ground point. Cable line locating is performed by measuring a local flux intensity of the locating signal at a first above ground point within the region using a portable locator in a particular orientation. A cable line angular orientation is established which limits the possible directions to the cable line relative to the particular orientation of the portable locator. The portable locator display is configured for periodic updates such that displayed positional relationships are essentially continuous, including accommodation of positional and/or orientation changes seen by the portable locator in dipole or cable line tracking.

Claims

1. In an overall system in which a boring tool is moved through the ground within a given region along a path while transmitting a locating signal such that the locating signal exhibits locate points at the surface of the ground, both ahead of and to the rear of the boring tool, a method comprising the steps of:

a) measuring a local flux intensity of the locating signal for at least one above ground point for use in establishing a horizontal flux vector at that point which is generally oriented in a horizontal plane; and

b) moving in a direction generally defined by the orientation of the horizontal flux vector as at least an intermediate step in establishing the position of a nearest one of the locate points.

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

c) at a new above ground point in said direction generally defined by the orientation of the horizontal flux vector, measuring a new local flux intensity to establish a new horizontal flux vector having a new orientation in the horizontal plane; and

d) moving in a new direction along the new horizontal flux vector.

3. The method of claim 2 wherein the horizontal flux vector is defined along an initial flux line and the new horizontal flux vector is defined along a new flux line that is different than the initial flux line such that more than one flux line is used in moving toward the boring tool.

4. The method of claim 1 wherein the boring tool is oriented horizontally, said method further comprising the steps of:

c) at the nearest locate point, measuring a locate point value of the flux intensity;

d) using the measured locate point value of the flux intensity, estimating the horizontal distance of the nearest locate point from the boring tool as well as the depth of the boring tool beneath the surface of the ground.

5. The method of claim 1 wherein the boring tool may exhibit pitch in moving underground, said method further comprising the steps of:

c) measuring the pitch of the boring tool;

d) at the nearest locate point, measuring a locate point value of the flux intensity;

e) using the measured value of the locating field and the pitch, estimating the horizontal distance, S, of the boring tool from the nearest locate point and the depth, D, of the boring tool beneath the surface of the ground.

6. The method of claim 5 wherein D and S are determined by the expressions

D=r sin(α

′

+φ

), and s=r cos(α

′

+φ

)

where φ

is pitch, b is a total flux intensity obtained from the measured local flux intensity and where r and α

′

are determined by

7. In an overall system in which a boring tool is moved through the ground within a given region along a path while transmitting a locating signal such that the locating signal exhibits locate points at the surface of the ground, both forward of and to the rear of the boring tool, a portable locator comprising:

a) a first arrangement for measuring a local flux intensity of the locating signal for at least one above ground point for use in establishing a horizontal flux vector at that point which is generally oriented in a horizontal plane; and

b) a second arrangement for indicating a direction generally defined by the orientation of the horizontal flux vector for use in establishing the position of a nearest one of the locate points.

8. The portable locator of claim 7 wherein the boring tool is oriented horizontally and wherein the portable locator further comprises:

c) a third arrangement for using the measured local flux intensity taken at the nearest locate point to estimate the horizontal distance of the locate point from the boring tool as well as the depth of the boring tool beneath the surface of the ground.

9. The portable locator of claim 7 wherein the boring tool may exhibit pitch in moving underground and wherein the portable locator further comprises:

c) a third arrangement for using the measured local flux intensity taken at he nearest locate point in combination with the pitch for estimating the horizontal distance of the boring tool from the nearest locate point and the depth of the boring tool beneath the surface of the ground.