TRACKING THE POSITIONAL RELATIONSHIP BETWEEN A BORING TOOL AND ONE OR MORE BURIED LINES USING A COMPOSITE MAGNETIC SIGNAL

• US 20110101985A1
• Filed: 01/07/2011
• Published: 05/05/2011
• Est. Priority Date: 05/03/1996
• Status: Active Grant

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Merlin Technologies Incorporated
• Inventors: Mercer, John E., Chau, Albert W.
• Granted Patent: US 8,188,746 B2
• Time in Patent Office: Days
• US Class Current: 324/326
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
• 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 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• 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 boring tool is moved through the ground in a region which includes at least one electrically conductive in-ground line and which is subject to static magnetic fields including the magnetic field of the earth. Tracking a positional relationship between the boring tool and the line, as well as a directional heading of the boring tool within the region are provided by: (i) generating a time varying magnetic field from the line; (ii) at the boring tool, detecting a composite magnetic signal which includes one component affected by the static magnetic fields and another component affected by the time varying magnetic field such that the static magnetic field component varies as a function of the directional heading and the time varying component varies as a function of the positional relationship; and (iii) processing the composite magnetic signal to separate the static magnetic field component and the time varying magnetic field component from the composite magnetic signal for use in determining the directional heading and the positional relationship. In one feature, the static magnetic field component is used to determine the directional heading of the boring tool and the time varying magnetic field component is used to determine the positional relationship.

Claims

1. In a system in which a boring tool is moved through the ground by a drill string in a region which includes at least one electronically conductive in-ground line, an arrangement for monitoring a specific positional relationship between the boring tool and said line, said arrangement comprising:

a first transmitter for generating a magnetic locating field from one of either said boring tool or at least an underground length of said line;

a receiver carried by said boring tool if said field is generated from said line, or connected to said line if said field is generated from said boring tool, for detecting an intensity of said magnetic locating field indicative of the positional relationship between the boring tool and said line;

a second transmitter carried by said boring tool for producing a locating signal; and

a portable locator for using said locating signal to determine a position of said boring tool within said region and for indicating the detected intensity of said magnetic locating field generated from either one of said line of said boring tool.

2. The apparatus of claim 1 wherein said portable locator includes an arrangement for establishing the specific positional relationship between said boring tool and said line.

3. The apparatus of claim 1 wherein the first transmitter arrangement and the receiver arrangement are cooperatively configured to provide the intensity of the magnetic locating field so as to be unambiguously representative of said specific positional relationship between the boring tool and the line.

4. The apparatus of claim 1 wherein the detected intensity indicated by said portable locator represents a vector sum.

5. The apparatus according to claim 1 including a telemetry link forming one part of said receiver arrangement and forming another part of said portable locator for transmitting the detected intensity from said boring tool or said line to said portable locator.