Velocity model building by 3D frequency-domain full-waveform inversion of wide-aperture seismic data

Hafedh Ben Hadj Ali (1) , Stéphane Operto (1) , J. Virieux (2)

1 GEOAZUR 6526 - Géoazur
2 LGIT - Laboratoire de Géophysique Interne et Tectonophysique

We assess 3D frequency-domain acoustic full-waveform inversion data as a tool to develop high-resolution velocity models from low-frequency global-offset data. The inverse problem is based on a classic gradient method. Inversion is applied to few discrete frequencies allowing management of a limited subset of the 3D data volume. The forward problem is solved with a finite-difference frequency-domain method based on a massively parallel direct solver allowing efficient multiple-shot simulations involving several thousands of sources. The inversion code is fully parallelized for distributed-memory platforms taking advantage of a domain decomposition of the modeled wavefields performed by the direct solver. After validation on simple synthetic tests, full-waveform inversion was applied to two targets (channel and thrust system) of the 3D SEG/EAGE overthrust model corresponding to 3D domains of 7 × 8.8 × 3.3 km3 and 13.5 × 13.5 × 4.65 km3 respectively. The maximum inverted frequencies were 15 Hz and 5 Hz for these 2 applications respectively. A maximum of 20 dual core biprocessor nodes with 8 gigabytes of share memory per node was used for the second case study. The main structures were successfully imaged at a resolution scale consistent with the inverted frequencies. This study confirms the feasibility of 3D frequency domain full-waveform inversion of global-offset data on large distributed-memory platforms to develop high-resolution velocity models. Further work is required to [i] perform more representative applications on larger computational platforms, [ii] assess the sensitivity of the 3D full-waveform inversion to the acquisition geometry and to the starting model and [iii] assess whether velocity models developed by full-waveform inversion can be used as improved background model for prestack depth migration.

Mots clés: finite difference methods; frequency-domain analysis; geophysical techniques; least squares approximations; seismic waves

Domaines: Géophysique [physics.geo-ph]; Géophysique [physics.geo-ph]

Hafedh Ben Hadj Ali, Stéphane Operto, J. Virieux. Velocity model building by 3D frequency-domain full-waveform inversion of wide-aperture seismic data. Geophysics, 2008, 73 (5), pp.VE101. ⟨10.1190/1.2957948⟩. ⟨insu-00200039⟩