Interpretation of incised valleys using new 3-D seismic techniques: A case history using spectral decomposition and coherency

New 3-D seismic interpretation techniques such as spectral decomposition and coherency have been shown to enhance interpretation of stratigraphic features in Tertiary, poorly lithified rocks, but their use has not been as well documented on older, more consolidated sediments. Coherency images seismic discontinuities by calculating localized seismic trace similarity. Spectral decomposition uses the discrete Fourier transform to image time thickness variability. In the latter, the amplitude spectrum, computed from a short time window covering the geologic zone of interest, is tuned by the rock properties within the analysis window. When applied to 3-D seismic and presented in map form, these spectral responses image lateral variability within the zone of interest.