Improving mini-basin and subsalt imaging with reflection full waveform inversion

Reflection-based full waveform inversion (RFWI) is increasingly used to recover long wavelengths of the background velocity model and provide updates that extend beyond the reach of diving waves. In our case study, we use an RFWI method that first updates the density using the high-wavenumber components of the decomposed full waveform inversion (FWI) gradient and then updates the velocity using the low-wavenumber components. We show on a deep water example from the Mexican side of the Perdido fold belt that RFWI improves the velocity inside the sediment mini-basins and thus the interpretability of the underlying salt. We also apply this method for the intra-salt and subsalt velocity updates and show how it can improve imaging of the deep targets.