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3D Near Surface Imaging Thanks to Refraction Tomography and Delay Method
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, Jun 2010, cp-161-00421
- ISBN: 978-90-73781-86-3
Abstract
The refraction seismic technique is being used increasingly to obtain 3D subsurface images to address geologic exploration and engineering problem. There are, however, several problems in solving the non-linear problem associated to the refraction travel time inversion. Thus it is important to develop inversion strategies for the 3D imaging of near surface structures. One set of high-resolution seismic data collected over an experimental hydrogeological site located near Poitier-France, designed to perform both 3D refraction and reflection seismic surveying, is processed using a first arrivals inversion to determine reliable 3D velocity model with special emphasis on upper part of the near-surface heterogeneous aquifer. The inversion strategy is a hybrid algorithm combining conventional delay method with refraction tomography and we show how this technique can be used to extend in the 0 – 35 m depth interval the 3D velocity block obtained by a previous reflection study. We investigate the impact that the change from 2D to 3D dimension in data has in the velocity imaging. The final result obtained with 3D data emphasizes the geological structures mentioned in the reflection image, allowing a better recognition of their alignments (N90°) and shape.