Boliden Mineral Ab

Robert Pantze

Stig Strombergsson

Henrik Sund&eacute;n

&Ouml;sten Lindqvist

Jan Wikberg

Lennart Wikman

Per Ederl&ouml;v

Per Nilsson

Svante Holmqvist

A transmitter for probing drill holes includes a ground-located conductor loop ( ) which is supplied with a current that has a wave shape which includes at least one low frequency (e.g., 200-3000 Hz). The frequency is crystal controlled and normalized to time signals from GPS satellites. A receiver includes coils which function to sense field changes having the same frequencies as the transmitter and is housed in a probe ( ). The probe is lowered with the aid of a typical drill pipe ( ) and lacks signal connection with the transmitter. Instead, the probe includes an accurate quartz clock which is frequently calibrated and which enables the phase of the received signal to be determined synthetically relative to the phase of the transmitter signal, e.g., by means of a signal processor.

Method of probing drill holes electromagnetically, and a transmitter arrangement and a receiver arrangement for carrying out the method

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.

Method for determining electromagnetically the locations of underground

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Boliden, Sweden

Robert Pantze