Diffraction wavefront tomography - efficient automated velocity inversion for multi-fold and single-channel data
A.B. Bauer, B.S. Schwarz and D.G. Gajewski
Event name: 80th EAGE Conference & Exhibition 2018 Workshop Programme
Session: WS01: Seismic Imaging with Ray and Waves - Where do we stand? Part I: Velocity Estimation
Publication date: 10 June 2018
Info: Extended abstract, PDF ( 2.29Mb )
Price: € 20
Seismic multi-channel acquisition offers the benefits of high data redundancy and improved illumination. However, large-offset recordings are generally expensive to acquire. For the case of passive seismic data, no offsets are available. Diffractions provide superior illumination compared to reflections, but typically have low amplitudes. However, diffractions possess unique properties, which bear the potential to improve the lateral resolution of inversion results. We present wavefront tomography as an efficient and stable tool for velocity inversion of both single-channel and multichannel as well as passive seismic data. For the case of single-channel data, we suggest an approach that reveals the diffracted background in the data through automated adaptive subtraction of the dominant reflected wavefield. Based on local stacking and coherence evaluation, the recorded diffracted events are treated as passive source wavefields characterized in terms of local properties of wavefronts emerging at the registration surface. The subsequently obtained inversion results are in good agreement with fault zones known from the local geology. In an industrial multi-channel field data example, we carried out a joint inversion of reflections and diffractions and present a laterally well-resolved velocity model, which we validate with reverse-time depth-migrated (RTM) results.