Scattering angle-based filtering via extension in velocity

Abstract

SUMMARYThe scattering angle between the source and receiver wavefields can be utilized in full-waveform inversion (FWI) and in reverse-time migration (RTM) for regularization and quality control or to remove low frequency artifacts. The access to the scattering angle information is costly as the relation between local image features and scattering angles has non-stationary nature. For the purpose of a more efficient scattering angle information extraction, we develop techniques that utilize the simplicity of the scattering angle based filters for constantvelocity background models. We split the background velocity model into several domains with different velocity ranges, generating an "extension in velocity". We establish an analytical relation between the proposed extension and conventional RTM images extended in time and show that extending with a few samples in the newly introduced dimension is sufficient to create a scattering angle based filter. Finally the new efficient algorithm is used in a conventional FWI scheme to filter the misfit gradients and improve inversion results.

Waveform inversion for orthorhombic anisotropy with P waves: feasibility and resolution

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