Inversino of controlled-source electromagnetic reflection responses

Abstract

Marine controlled-source electromagnetic reflection responses can be retrieved by interferometry. These reflection responses are free of effects related to the water layer and the air above it and do not suffer from uncertainties related to the source position and orientation. Interferometry is a data-driven process requiring proper sampling of the electromagnetic field as well as knowledge of the material parameters at the receiver level, i.e., the sediment just below the receivers. We have inverted synthetic data sets using the reflection responses or the original electromagnetic fields with the goal of extracting the conductivity model of the subsurface. For the inversion, a genetic algorithm and a nonlinear conjugate-gradient algorithm were used. Our results show that an inversion of the reflection responses produces worse estimates of the vertical conductivity but superior estimates of the horizontal conductivity (especially for the reservoir) with respect to the original electromagnetic fields.