Patent ID: 6617854
Filing Date: 2003-09-09
Classification: E21B,G01V

Abstract:
In a system including a boring tool and a drill string having a length which is fed out to move the boring tool through the ground in a region which includes a plurality of electrically conductive in-ground lines, a method for tracking the specific positional relationships between the boring tool and each of said lines, said method comprising the steps of:a) generating a magnetic field from said boring tool; b) connecting one of a plurality of detector means to each respective one of said lines; c) detecting a relative change in a particular characteristic of said field using the detector means, 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; d) monitoring a value of at least one parameter relating to the way in which said drill string is fed out; and e) 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.