The Time Domain Borehole Electromagnetic method measures the response to the propagation of an electromagnetic field in the vicinity of a borehole.

The acquisition method consists of the transmission of an electromagnetic wave (primary field) in the subsurface by means of a coil located on the surface, through which an electric current circulates. When the primary field reaches a conductive body at depth, a response called secondary field is generated, which is detected by the receiving probe through the borehole.

Through analysis and interpretation, the method allows the detection of massive sulfide bodies to a maximum depth of 1000 m and to a radius of 200 m from the borehole axis.