Tracking the positional relationship between a boring tool and one or more buried lines using a composite magnetic signal

• US 6,191,585 B1
• Filed: 05/27/1999
• Issued: 02/20/2001
• Est. Priority Date: 05/03/1996
• Status: Expired due to Term

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Digital Control Incorporated
• Inventors: Mercer, John E., Chau, Albert W.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US09/321,151
• Time in Patent Office: 635 Days
• Field of Search: 324/326, 324/327, 324/328, 324/329, 324/345, 324/346, 324/226, 324/225, 324/232, 324/207.23, 175/40, 175/45
• 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 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, a method of tracking a positional relationship between the boring tool and said line as well as determining a directional heading of the boring tool within said region, said method comprising the steps of:

a) generating a time varying magnetic field from said line;

b) at said boring tool, performing measurements for use in producing a composite magnetic signal which includes one component affected by said static magnetic fields and another component affected by said time varying magnetic field such that the static magnetic field component varies as a function of said directional heading and the time varying component of the detected composite magnetic signal varies as a function of said positional relationship; and

c) processing said composite magnetic signal in a way which separates the static magnetic field component and the time varying magnetic field component from the composite magnetic signal for use in determining said directional heading and said positional relationship.

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

d) using the static magnetic field component to determine said directional heading of the boring tool and using the time varying magnetic field component to determine said positional relationship.

3. The method of claim 1 wherein said measuring step includes the steps of measuring magnetic data and acceleration data for use in establishing the composite magnetic signal.

4. The method of claim 3 wherein said magnetic data and said acceleration data are each measured along three orthogonal axes.

5. The method of claim 3 wherein said processing step includes the step of transforming the measured magnetic data based on said acceleration data at a particular point in time to compensate for instantaneous orientation of the boring tool.

6. The method of claim 3 wherein the orientation of said boring tool within said region includes a pitch value and a roll value and wherein said processing step includes the step of using said acceleration data to determine roll and pitch orientation.

7. The method of claim 3 including the step of displaying said acceleration data and said magnetic data in a predetermined way at an above ground location.

8. The method of claim 7 wherein said acceleration data is displayed in terms of individual accelerations and said magnetic data is used to present the heading of the boring tool based on compass directions.

9. The method of claim 7 wherein said acceleration data is displayed in terms of the roll and pitch orientation of the boring tool and said magnetic data is used to present the heading of the boring tool based on compass directions.

10. In a system in which 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, a method of tracking a positional relationship between the boring tool and said line as well as a directional heading of the boring tool within said region, an arrangement for tracking a positional relationship between the boring tool and said line as well as a directional heading of the boring tool within said region, said arrangement comprising:

a) means for generating a time varying magnetic field from said line;

b) a detecting arrangement at said boring tool for detecting a composite magnetic signal which includes one component affected by said static magnetic fields and another component affected by said time varying magnetic field such that the static magnetic field component varies as a function of said directional heading and the time varying component of the detected composite magnetic signal varies as a function of said positional relationship;

c) processing means for processing said composite magnetic signal in a way which separates the static magnetic field component and the time varying magnetic field component from the composite magnetic signal for use in determining said directional heading and said positional relationship.

11. The arrangement of claim 10 including means forming part of said processing means for using the static magnetic field component to determine said directional heading of the boring tool and using the time varying magnetic field component to determine said positional relationship.

12. The arrangement of claim 10 wherein said detecting arrangement includes means for measuring magnetic data and acceleration data for use in establishing the composite magnetic signal.

13. The arrangement of claim 12 wherein said magnetic data and said acceleration data are each measured along three orthogonal axes.

14. The arrangement of claim 12 wherein said processing means includes means for transforming the measured magnetic data based on said acceleration data at a particular point in time to compensate for instantaneous orientation of the boring tool.

15. The arrangement of claim 12 wherein the orientation of said boring tool within said region includes a pitch value and a roll value and wherein said processing means includes means for using said acceleration data to determine roll and pitch orientation.

16. The arrangement of claim 12 further comprising display means for displaying said acceleration data and said magnetic data in a predetermined way at an above ground location.

17. The arrangement of claim 16 wherein said acceleration data is displayed in terms of individual accelerations and said magnetic data is used to present the heading of the boring tool based on compass directions.

18. The arrangement of claim 16 wherein said acceleration data is displayed in terms of the roll and pitch orientation of the boring tool and said magnetic data is used to present the heading of the boring tool based on compass directions.