Inversion on Reflected Seismic Wave

Abstract

Full waveform inversion has been successful in building high resolution velocity models for shallow layers. To be successful, it requires refracted waves or low frequencies in the reflection/refraction data. We revisit full waveform inversion theory in hopes of relaxing the dependence on low frequency reflections. We implement an approach allowing the updating of long wavelength components of the velocity model affecting the reflected arrivals even with absence of low frequency in the input data. Our tactic is based on a non-linear iterative relaxation approach where short and long wavelength components of the velocity model are updated alternatively. We study theoretically the associated Fréchet derivatives and gradients and discussed how and why such a strategy improves the resolution that we can expect from full waveform inversion. The kernel of our approach is very similar to the algorithm of migration based travel time tomography proposed by Chavent et al. (1994). Finally we present a preliminary 2D application to a 2D Gulf of Mexico conventional streamer dataset.