Tracking the positional relationship between a boring tool and one or more buried lines using a composite magnetic signal
First Claim
1. In a system in which a boring tool is connected to a drill string having a length which is fed out in a way which moves the boring tool through the ground in a region which includes a plurality of electrically conductive in-ground lines, an arrangement for tracking a plurality of positional relationships between the boring tool and each of said lines, a configuration comprising:
- a transmitter arrangement for generating a mmgnetic field from said boring tool;
a plurality of detector arrangements, each of which is connected with a respective one of said lines, for detecting a relative change in a characteristic of said field, which characteristic varies as a function of said specific positional relationship between said boring tool and each of said lines as the boring tool moves through the ground within said region;
a monitoring arrangement for monitoring a value of at least one parameter relating to the way in which said drill string is fed out; and
a processing arrangement cooperating with said plurality of detector arrangements for correlating the detected relative changes in said characteristic with the value of said one parameter in a way which indicates certain changes in the positional relationship between said boring tool and each respective line without the need to establish an actual distance between the boring tool and each line.
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Accused Products
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 tie 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.
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Citations
18 Claims
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1. In a system in which a boring tool is connected to a drill string having a length which is fed out in a way which moves the boring tool through the ground in a region which includes a plurality of electrically conductive in-ground lines, an arrangement for tracking a plurality of positional relationships between the boring tool and each of said lines, a configuration comprising:
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a transmitter arrangement for generating a mmgnetic field from said boring tool;
a plurality of detector arrangements, each of which is connected with a respective one of said lines, for detecting a relative change in a characteristic of said field, which characteristic varies as a function of said specific positional relationship between said boring tool and each of said lines as the boring tool moves through the ground within said region;
a monitoring arrangement for monitoring a value of at least one parameter relating to the way in which said drill string is fed out; and
a processing arrangement cooperating with said plurality of detector arrangements for correlating the detected relative changes in said characteristic with the value of said one parameter in a way which indicates certain changes in the positional relationship between said boring tool and each respective line without the need to establish an actual distance between the boring tool and each line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 14, 15, 16, 17, 18)
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- 9. A configuration according to claim 9 wherein said transmission/control arrangement includes means for selectively driving each one of said three antennas at a different frequency.
Specification