Method and arrangement for locating a boring tool using a three-antennae vector sum

• US 5,990,683 A
• Filed: 04/13/1998
• Issued: 11/23/1999
• Est. Priority Date: 03/01/1991
• Status: Expired due to Fees

• Current Assignee: Merlin Technologies Incorporated
• Original Assignee: Digital Control Incorporated
• Inventors: Mercer, John E.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US09/059,617
• Time in Patent Office: 589 Days
• Field of Search: 324/326-329, 324/226, 324/247, 175/40, 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: E21B 47/024 of devices in the borehole determining slope or direction of the borehole E21B47/022
• 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 3/165 operating with magnetic or electric fields produced or modified by the object or by the detecting device with electromagnetic waves G01V3/17

Abstract

The present invention provides a locator/monitor capable of locating a boring tool and monitoring the progress of the tool for control purposes. The locator/monitor may be used in expedited locating methodology and straightforward calibration techniques of the present invention. A durable and cost effective pitch sensor is also provided by the present invention. In addition, the present invention provides a slotted transmitter housing formed of an electrically conductive material, where the magnetic field generated by the transmitter is capable of penetrating to the surface.

Claims

1. A method of determining the distance between a point of observation and a generally horizontally extending dipole magnetic field transmitter which is beneath the point of observation and disposed within a given vertical plane, comprising the steps of:

(a) measuring the field strength of the magnetic field at the point of observation using three antennae, a first two of which are disposed within said given vertical plane and oriented orthogonally to each other and the third one of which is orthogonal to the plane defined by the first two antennae

(b) calculating the distance between the point of observation and the transmitter as a function of the vector sum of the field strengths measured by the antennae; and

(c) displaying the calculated distance.

3. A method according to claim 1 wherein the first two of said antennae are oriented at angles of 45 degrees with the horizontal.

2. An arrangement for determining the distance between a point of observation and a generally horizontally extending dipole magnetic field transmitter which is beneath the point of observation and disposed within a given vertical plane, said arrangement comprising:

(a) means for measuring the field strength of the magnetic field at the point of observation using three antennae, a first two of which are disposed within said given vertical plane and oriented orthogonally to each other and the third one of which is orthogonal to the plane defined by the first two antennae;

(b) means for calculating the distance between the point of observation and the transmitter as a function of the vector sum of the field strengths measured by the antennae; and

(c) means for displaying the calculated distance.

4. A system according to claim 2 wherein the first two of said antennae are oriented at angles of 45 degrees with the horizontal.

5. A method of determining a numeric value that is a monotonic function of the distance between a point of observation and a generally horizontally extending dipole magnetic field transmitter which is beneath the surface of the ground, comprising the steps of:

(a) measuring the field strength of the magnetic field at the point of observation using three antennae which are orthogonal to one another;

(b) calculating a numeric value that is a monotonic function of the distance between the point of observation and the transmitter as a function of the vector sum of the field strengths measured by the antennae; and

(c) displaying the calculated numeric value.

6. An arrangement for determining a numeric value that is a monotonic function of the distance between a point of observation and a generally horizontally extending dipole magnetic field transmitter which is beneath the surface of the ground, said arrangement comprising:

(a) means for measuring the field strength of the magnetic field at the point of observation using three antennae which are orthogonal to one another;

(b) means for calculating a numeric value that is a monotonic function of distance between the point of observation and the transmitter as a function of the vector sum of the field strengths measured by the antennae; and

(c) means for displaying the calculated numeric value.