CSEM Sensitivity Analysis Through Resolution Functions for Migration and Inversion

CSEM acquisition optimization is of interest to reduce acquisition costs, while maintaining the information content information in the data high. Fast methods for sensitivity analysis are useful to perform this task. We define a resolution function for migration and the resolution function for inversion to obtain an indication of s possible inversion result from acquired CSEM data. We model a conductivity perturbation in a conductive VTI lower half-space below a non-conductive lower half-space. We show that the resolution function for migration is capable of indicating the horizontal position of the perturbation, but not its depth. The introduced resolution function for inversion is shown to have a good horizontal and vertical resolution, where the horizontal resolution is virtually independent of the perturbation depth, while the vertical resolution decreases with increasing perturbation depth. In a VTI background medium, it seems that it is more important to accurately know the horizontal conductivity than it is to know vertical conductivity.