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Strongly absorptive geologic bodies in the near surface, particularly from gas trapped beneath hydrates, have been a significant seismic challenge for the accurate identification and interpretation of deeper oil and gas reservoirs. In this case history, we show how the inverted Q model can compensate for the effects of amplitude loss, phase distortion and velocity dispersion seen in the recently acquired time-lapse ocean bottom node (OBN) surveys. The results of the inverted Q model are located at the same position as the low velocity anomalies derived from full waveform inversion (FWI) and align with the bright shallow structures, giving us confidence in the image compensation using this Q model. The compensation results show that the events become sharper and the structures more coherent for both Q-Kirchhoff PSDM and Q-RTM (Reverse Time Migration) imaging. We also show the impact on the 4D interpretation of the baseline and monitor 4D OBN surveys. Early interpretation results indicate the Q compensated data gives a much closer match between the 4D results and the earth model predictions.

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TX 75083-3836, U.S.A., fax 01-972-952-9435.