 Phase Reversal
1. Do both the top and base reservoir show phase reversals?
2. Is the amplitude of the flat spot always higher than that of the top reservoir, it should be?
3. Is the amplitude of the flat spot higher than that of the base reservoir, it almost always is, except where the base seal unit is extremely high or low impedance (e.g. the reservoir rests directly upon basement or overpressured shales)?
4. Do you see constructive interference on the top reservoir (super bright), where the side lobe of the flat spot impinges on the trough of the top reservoir?
5. Do you see constructive interference on the base reservoir (super bright), where the side lobe of the flat spot impinges on the trough of the top reservoir?
6. Is the flat spot the opposite polarity to the top reservoir?
7. Is the point of the phase change consistent with structure in depth?
8. Is the phase change consistent with the polarity and phase assumptions?
9. Have you considered non hydrocarbon explanations for the phase reversal, i.e. changes in the encasing shale or faulting?
10. Do you observe an AVO anomaly and does it match your modelled response?
Note: if the hydrocarbon column is less than the thickness of the reservoir, you will not observe the base reservoir effects.
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