Patent ID: 9638028
Date: 2017-05-02
CPC Classifications: E21B,G01V,Y02A

Claim:
1. A method for signal communication between a well drilling instrument and the Earth's surface, comprising: generating an electromagnetic field in an instrument disposed in a drill string used to drill a wellbore, the electromagnetic field comprising encoded measurements from at least one sensor associated with the instrument; measuring a signal corresponding to an amplitude of the electromagnetic field; and decoding the measurements from the measured signal, wherein the signal comprises at least one of; wherein the selected depth is at least a bottom depth of a shallowest formation below a water table having a highest resistivity within 500 meters of the surface and wherein the selected lateral distance comprises a distance from a drilling unit wherein electrical noise amplitude therefrom is reduced by at least a factor of two from the noise amplitude at a distance of 50 meters from the drilling unit.