What initial velocity model do we need for full waveform inversion?

In the context of velocity model building, we examine if the velocity models obtained after<br>first-arrival traveltime tomography are accurate enough for subsequent full waveform<br>inversion of reflected energy. For that purpose, we test the quality of the velocity model<br>obtained by first-arrival traveltime tomography on the BP salt dome model. Several 1-D<br>inversions are conducted in two different zones. In the simplest zone corresponding to smooth<br>velocity models, the tomographic models are good enough for waveform inversion with<br>realistic frequency contents. In the complex part going through a salt body, one need very low<br>frequencies (starting at around 1 Hz) or a further refinement of the tomographic model.