High resolution Full Waveform Inversion: two pitfalls and a remedy

FWI velocity models do not necessarily ensure an optimal flattening of common image gathers (CIG). A fundamental reason for this is that mid to high wavenumbers are brought into the model by the reflection amplitudes, which are only partly explained by changes in velocity. A residual low wavenumber update of the model is then frequently done with the consequence that the positioning of small-scale events in the model may no more be consistent with the migrated image. In this paper we first highlight and illustrate the above mentioned pitfalls. We then propose an innovative workflow based on FWI-guided tomography.