DEFF
Inversion approaches can give remarkable images of the subsurface and return quantitative information on the resistivity of the various subsurface materials.
DEFF provides an alternative approach that creates images of the earth by detecting the location of geo-electric boundaries in the subsurface using a process which is similar in principle to seismic wavefield migration.
The Diffusive E-field Focusing (DEFF) method is a wavefield continuation imaging approach using marine CSEM data. DEFF uses plane-wave downward continuation to reconstruct electrical property contrasts given surface recorded electric fields. The technique is a narrow-band imaging method typically employing less than 10 discrete frequencies.
The result is an interpretable geo-electric depth-section that resolves relative resistivity boundaries and detects thin resistive layers.
In contrast to 2D inversion, DEFF includes an approximation to the equations governing the propagation of EM energy in a conductive medium. As such, results should not be considered as robust as a full 2.5D inversion.