Dual Transmitter–Receiver Electromagnetic System for Lateral Boundary Detection of Subsurface Formations

A new frequency domain electromagnetic system, based on different working principle has been designed and its efficacy tested over the existing systems through laboratory-scale-model studies. In this system, two transmitter coils have been employed to generate a magnetic null plane at their geometric centre. The receiver coil is placed in the null plane to record the induced secondary field. The interaction of the primary field is almost negligible on the secondary field recorded by the receiver. We present the theory and physical model results describing the system parameters and efficacy. The testing through physical model studies suggests an increased depth of detection in this new configuration compared to the existing systems. In terms of secondary field, the strength of the anomaly reflects the magnetic permeability/susceptibility difference of the subsurface medium on either side of the receiver. The study concludes that there is significant increase in depth of investigation and secondary field strength in this system over the existing conventional frequency domain systems and also more robust for boundary detection.