Electromagnetic (EM) techniques are used to map conductivity variations within the earth. A time-varying magnetic field is established by passing an electrical current through a very long wire. This primary field generates eddy currents in a conductive medium. These eddy currents in turn generate a secondary EM field which is diagnostic of the electrical characteristics of the conductive medium excited by the primary field.
The UTEM borehole and surface systems (operated with Lamontagne Geophysics Ltd.) are designed to achieve the necessary sensitivity and interpretability to deal with the problems of deep exploration, conductive environments and a variety of terrain conditions, and to do so economically. The greatest advantage of the system lies in its unique waveform, which allows the UTEM receiver to sample the step response of the ground with a high signal to noise ratio. Unlike “pulse” systems that measure only during their transmitter’s off-time, the UTEM system measures the whole response continuously.
Applications
- Locating contaminant plumes and buried metallic objects
- Mapping lateral and vertical conductivity
- Monitoring groundwater quality at landfills
- Locating steeply dipping bedrock fractures
- Deep exploration
- Reconnaissance exploration
- Borehole geophysical logging
