Method for preventing the drilling of a new well into one of a plurality of production wells

Claim 1

A method for preventing the drilling of a first well into any one of a plurality of second wells, comprising the steps of: (a) lowering a borehole tool into one of said plurality of second wells and injecting an alternating current flow into the well casing of said well from said tool at a selected depth point such that a first magnetic field is created above said point of injection around said well due to the difference in the opposing current flows downward through said borehole tool and its support cable to said point of injection and upward through said well casing from said point of injection and a second magnetic field is created below said point of injection around said well casing due to the downward current flow from said point of injection, said first and second magnetic fields being equal in both direction and magnitude so as to create a uniform magnetic field along the length of the well casing both above and below said point of injection, (b) repeating step (a) for each of the remaining ones of said second wells utilizing a differing alternating current frequency for each of said second wells to create a magnetic field around each of said second wells, each of said magnetic fields having a differing detectable characteristic based on the phase of the alternating current creating said magnetic field, (c) locating a magnetometer in a non-magnetic section of the drill string of said first well, (d) measuring the magnetic field intercepted by said magnetometer during the drilling of said first well, and (e) redirecting the drilling of said first well when the measurement of said magnetic field indicates that the continued drilling of said first well would result in the intersection of said first well with one of said second wells.

Claim 2

A method for preventing the drilling of a first well into any one of a plurality of second wells, comprising the steps of: (a) lowering a borehole tool into one of said plurality of second wells and injecting an alternating current flow into the well casing of said well from said tool at a selected depth point such that a first magnetic field is created above said point of injection around said well due to the difference in the opposing current flows downward through said borehole tool and its support cable to said point of injection and upward through said well casing from said point of injection and a second magnetic field is created below said point of injection around said well casing due to the downward current flow from said point of injection, said first and second magnetic fields being equal in both direction and magnitude so as to create a uniform magnetic field along the length of the well casing both above and below said point of injection, (b) repeating step (a) for each of the remaining ones of said second wells utilizing a differing alternating current frequency for each of said second wells to create a magnetic field around each of said second wells, each of said magnetic fields having a differing detectable characteristic based on the phase of the alternating current creating said magnetic field, (c) locating a magnetometer in a non-magnetic section of the drill string of said first well, (d) measuring the magnetic field intercepted by said magnetometer during the drilling of said first well, and (e) redirecting the drilling of said first well when the measurement of said magnetic field indicates that the continued drilling of said first well would result in the intersection of said first well with one of said second wells.