Conductivity-depth imaging of time-domain EM data based on pseudo-layer half-space model

A conductivity depth imaging (CDI) algorithm for concentric-coil helicopter time-domain electromagnetic (HTEM) systems is developed based on the pseudo-layer half-space model. The primary advantages of this model are immunity to altimeter errors, and a bias towards conductive layers. Effective depth is derived empirically from the computed conductivity, sampling time, and apparent thickness of the pseudo-layer. A table lookup procedure is created based on the analytic solution to the half-space models to speed up the processing. This efficiency makes the generation of real-time CDIs possible. Tests of the program on synthetic and field data yield stable and geologically meaningful results.