In land data acquisition, imaging the near sub-surface remains a difficult task due to complex wave propagation effects. In this context, Full Waveform Inversion (FWI) is potentially an attractive method. FWI aims at retrieving the Earth properties from pre-stack seismic data. In practice, the method is highly non-linear, thus suffering from many local minima (Bunks et al., 1995). The first gradient of the FWI approach has been recognized as being equivalent to a migration step (Tarantola, 1984), This provides the short wavelengths of the velocity model, also known as being the reflectivity part. However, major difficulties are encountered to update the background velocity model associated to the long wavelengths of the model.
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