The joint time-frequency and time-phase analysis applied to a field seismic data highlights lateral changes on preferential frequency and phase illumination at the target across secondary faults. Mutual thin-bed interference modeling suited for the case study area was performed using a well-tying well-based extracted wavelet assumed to be representative of the wavelet embedded on the input seismic data. The long coda of this wavelet is also present on the corresponding thin-bed waveform, indicating the possibility of more complex mutual interference patterns between thin beds and mutual interference at farther vertical separations between thin beds compared with what would occur for an embedded wavelet with a shorter coda. The observed lateral changes on preferential frequency and phase illumination on the seismic data are attributable to collocated lateral changes in the stacking patterns and variable occurrence of vertically adjacent thin beds, which are interpreted as lateral sediment deposition changes induced by the syndepositional activity of the secondary faults. This is a geologic scenario that had not been previously considered on the area until the evidence of this case study provide indirect support for it.

Using time-frequency and time-phase analysis we found that for an isolated thin bed in a binary-impedance setting, there is no observable sensitivity in preferential illumination as layered net-to-gross (NTG) changes within the isolated thin bed, regardless of the way the internal layering is distributed — either uniformly or semirandomly. The NTG signature is observed on the amplitude (magnitude) responses, rather than any specific frequency or phase component. On the other hand, external mutual thin-bed interference can significantly change the preferred phase component for each participating target. This phenomenon is largely driven by the embedded seismic wavelet that determines the nominal seismic response of an isolated thin layer and what phase component would preferentially illuminate it. For vertical separations between mutually interfering and elastically comparable thin beds in which mutual constructive interference is achieved, the target bed will be preferentially illuminated at a phase component that is very close to that of a total seismic isolation, whereas the occurrence of mutual destructive interference will cause a significant departure on the phase preferential illumination from that of an isolated seismic thin bed. All these observations can provide an avenue to yield more robust stratigraphic interpretations of seismic data and enhance the confidence on subsurface description.

Phase decomposition is applied to low-impedance hydrocarbon-bearing sands in a clastic section where sand thicknesses vary from the vicinity of tuning to well below tuning. Through Phase Decomposition the amplitudes separate into the expected phase components, resulting in a different spatial distribution of mapped amplitudes than on the original seismic data.

Phase Decomposition separates the trace into a 2D function of amplitude versus time and phase. The amplitude variation with time for a specific seismic phase is referred to as a phase component. Subtle lateral impedance variations occurring within thin layers can be greatly amplified in their seismic expression when specific phase components are isolated. For seismically thin layers, phase components are particularly useful in simplifying seismic interpretation.

Phase decomposition is used as a Direct Hydrocarbon Indicator in low impedance light oil bearing sands in a deepwater Gulf of Mexico seismic dataset. Amplitude anomalies are laterally distributed among phase components, showing, for reservoirs of similar properties (including thickness), an evident separation between oil bearing and brine bearing reservoirs. The tuning thickness of the reservoir is determined by applying the technique in synthetic gathers, which provide a guideline to define the required dominant frequency of the seismic data prior application of the attribute.