High resolution seismic imaging in shallow salt environment: preliminary results from the SEFASILS campaign, NS11A-04 - Archive ouverte HAL
Communication Dans Un Congrès Année : 2019

High resolution seismic imaging in shallow salt environment: preliminary results from the SEFASILS campaign, NS11A-04

Jean-Xavier Dessa
Serge Sambolian
Mohamed Bachir Miguil
  • Fonction : Auteur
Laure Schenini
Stéphane Operto
Alessandra Ribodetti
  • Fonction : Auteur
Marie-Odile Beslier
Christophe Larroque

Résumé

In the last decade, seismic imaging below salt/basaltic bodies proved beyond doubt to be the most challenging task using conventional strategies in terms of surveying, processing and inversion. Recent innovations across the whole workflow pushed further the resolution limit in such complex environments for resource exploration purposes. On the other hand, for instance, the western Mediterranean basin, a fairly studied seismogenic zone, still raises some questions due to the lack of clear-cut imaging results. The latter is caused by the presence of the ill-famed Messinian salt at shallow depth in this region which generates a wavefield dominated by backscattering and diffractions due to the abrupt high velocity contrast and structural complexity. We take a fresh look at a new batch of towed-streamer data acquired in the Ligurian basin during the SEFASILS campaign. During this study, we examine preliminary results using a conventional velocity model building strategy based on velocity analysis techniques and another based on a state of the art tomographic method. We review the theory behind slope tomography, a reflection/diffraction tomography method based upon inversion of locally-coherent events. A locally-coherent seismic event, described by its two-way traveltimes and the slopes, in a common-shot or common-receiver gather can be interpreted as a reflection/diffraction from a small reflector segment or diffractor in depth. A key advantage of slope tomography methods in such settings is the automatic densely picked data cube of locally-coherent events opposed to a very challenging tracking of continuous events. We also explain the advantages of our parsimonious formulation in tackling the velocity-position trade-off. We illustrate the resolution power of slope tomography compared to more conventional techniques. We point out the main challenges and insurmountable obstacles encountered while assessing the quality of the reconstructed models and depth migrated images.
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Dates et versions

hal-02381967 , version 1 (26-11-2019)

Identifiants

  • HAL Id : hal-02381967 , version 1

Citer

Jean-Xavier Dessa, Serge Sambolian, Mohamed Bachir Miguil, Laure Schenini, Stéphane Operto, et al.. High resolution seismic imaging in shallow salt environment: preliminary results from the SEFASILS campaign, NS11A-04. AGU Fall Meeting, Dec 2019, San Francisco, United States. ⟨hal-02381967⟩
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