BUCKING COIL AND B-FIELD MEASUREMENT SYSTEM AND APPARATUS FOR TIME DOMAIN ELECTROMAGNETIC MEASUREMENTS

摘要

According to one example embodiment is a time domain electromagnetic (TDEM)geophysical survey system for producing a B-field measurement, comprising: atransmitter coil; a bucking coil positioned in a substantially concentric andcoplanarorientation relative to the transmitter coil; a receiver coll positioned in asubstantially concentric and coplanar orientation relative to the buckingcoil; anelectrical current source connected to the transmitter coil and bucking coilforapplying a periodic current thereto; and a data collection system configuredtoreceive a magnetic field time-derivative signal dB/dt from the receiver coilandintegrate the magnetic field time-derivative signal dB/dt to generate amagnetic B-fieldmeasurement, the transmitter coil, bucking coil and receiver coil beingpositioned relative to each other such that, at the location of the receivercoil, amagnetic field generated by the bucking coil has a cancelling effect on aprimarymagnetic field generated by the transmitter coil.