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Communication Dans Un Congrès Année : 2010

Building starting model for full waveform inversion from wide-aperture data by stereotomography

V. Prieux
  • Fonction : Auteur
S. Operto
G. Lambaré
  • Fonction : Auteur

Résumé

Building reliable starting model remains one of the most topical issue for successful application of full waveform inversion (FWI). In this study, we assess the stereotomography as a tool to build reliable starting model for frequency-domain FWI from long offset (i.e., wide-aperture) data. Stereotomography is a slope tomography method based on the use of traveltimes and slopes of locally-coherent events in the data cube. We assessed a tomographic workflow based on stereotomography and frequency-domain FWI on the 2D acoustic synthetic Val- hall case study. We first computed an acoustic full-wavefield dataset using a finite-difference time-domain modeling engine for a wide-aperture survey with a maximum offset of 24 km. The source bandwidth is between 10 and 45 Hz. Compared to a conventional application of stereotomography, we investigate in this study the benefits provided by the joint inversion of refraction and reflection traveltimes from long-offset data. The use of refraction traveltimes is expected to stabilize and improve the reconstruction of the shallow part of the model. In a similar way as for frequency-domain FWI, we design a multiscale approach which proceeds hierarchically from the wide-aperture to the short-aperture angles to mitigate the non linearity of the inversion. The starting models for FWI were built by stereotomography using three sets of picked events. For the first data set, the picking is limited to reflection travel- times for a maximum offset of 4 km. For the second data set, both refracted and reflected events were picked using an acquisition with a maximum offsets of ± 16 km. In a third test, we extended the maximum offsets to ± 24 km offset for first- arrival travel time picking. We highlight the improvements of the FWI results obtained from the starting stereotomographic model built from the long-offset data set. The improvements due to the use of long offsets data are observed at the reservoir level below the gas layers but also in the upper part of the model where the joint use of refraction and reflection travel- times is helpful to improve the ray illumination. ©2010 Society of Exploration Geophysicists
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Dates et versions

hal-00719039 , version 1 (18-07-2012)

Identifiants

Citer

V. Prieux, S. Operto, G. Lambaré, J. Virieux. Building starting model for full waveform inversion from wide-aperture data by stereotomography. The Society of Exploration Geophysicists (SEG 2010), Oct 2010, Denver, United States. pp.988, ⟨10.1190/1.3513942⟩. ⟨hal-00719039⟩
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