Importance

Loading Importance Indicators...

Abstract

A method and apparatus for determining electromagnetically the locations of electrically conductive bodies beneath the surface of the ground, wherein a primary electromagnetic field is generated with the aid of a loop through which a sinusoidal alternating current is passed. The loop is placed at or above the level of the ground beneath which the locations of conductive bodies shall be determined. There are currents generated in the conductive bodies which, in turn, generate a secondary electromagnetic field. The values of the amplitude and phase of the magnetic component of the thus formed total electromagnetic field are measured with the aid of coils mounted inside a probe which is lowered to different depths in a borehole. The values of the primary field phase are measured continuously by at least one reference coil which is placed outside the probe, either above or beneath the surface of the ground, within the propagation area of the primary field. The reference coil is orientated so as to receive at least one component of the magnetic field and the signals obtained form the reference coil, or the result of the processed signals, are transmitted to the receiver on a transmission line.

Loading the Abstract Image...

First Claim