Combining multiple components of infiniTEM electromagnetic data to better represent subsurface anomalies

Abstract

Time-domain electromagnetic (TDEM) surveys rely on electromagnetic induction from a time varying magnetic field to produce recordable responses from conductive material in the subsurface. Interpretation of TDEM data is dependent on the location of a conductor in relation to the primary field of the transmitter and therefore can be very complicated. This is especially true for the InfiniTEM® figure 8 transmitter configuration where the same vertical conducting plate can produce a variety of signatures depending on its location relative to the transmitter loop. This study investigates the usefulness of the energy envelope processing technique to combine multiple components of InfiniTEM® survey data to remove the directional dependance on the primary field. The energy envelope involves adding the vertical and horizontal components responses with associated Hilbert transforms in quadrature to create a single profile peaking over the location of an anomaly. This approach provides a more intuitive contour map for interpretation.