Frequency Effects at Pre-, Near- and Post-critical Offsets Observed on Water-plexiglas Interface

In time-lapse seismic surveys, changes in the medium properties are anticipated only in specific locations of the subsurface. These locations are usually limited to reservoir layers where fluid substitution occurs. Elsewhere, the seismic response is expected to remain the same over time. We introduce an impedance anamorphosis to correct for unlikely seismic impedance changes that may appear in 4D seismic inversion as a result of the "zero-mean" property of the reconstructed model. Results obtained with a simple synthetic example and with real seismic data acquired over the Sleipner CO2 storage demonstrate the effectiveness of the method.