Full waveform inversion (FWI) derived reflectivity (FDR) is a derivative product of FWI velocity models. FDR provides improved images below complex overburden compared to conventional seismic imaging. The next objective is to leverage FDR volumes to extract attributes for reservoir characterization. However, one should first understand the meaning of FDR amplitude in terms of elastic properties. In theory, FDR, which is derived from the FWI velocity, should be a derivative response of velocity, and a P-wave sonic log should be used to calibrate FDR before interpretation. While elastic FWI is a cutting-edge approach, current processing practices commonly use acoustic FWI with constant density. In analyzing acoustic FWI models at multiple wells from offshore Trinidad, we observe that the FWI velocity model correlates more strongly with acoustic or elastic impedance than with P-wave velocity. Therefore, we suggest using acoustic or elastic impedance well logs for the seismic well-tie and calibration of FDR volumes derived from an acoustic FWI model. This ensures a more accurate interpretation of FDR data in context of reservoir characterization.

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