Efficient 3D elastic FWI using a spectral-element method on Cartesian-based mesh
Résumé
Full Waveform Inversion offers the possibility to extract high-resolution quantitative multi-parameters models of the subsur-face from seismic data. Heretofore, most of FWI applications at the crustal scale have been performed under the acoustic approximation, generally for marine environments. When considering challenging land problems, efficient strategies are required for moving toward elastic inversion. We present such approach for 3D elastic time-domain inversion, based on spectral element methods designed on cartesian-based meshes. The proposed workflow integrates an easy and accurate cartesian-based mesh building with high-order shape functions to capture rapid topography variations and an efficient workflow for the incident and adjoint fields computation. A nonstationary and anisotropic structure-oriented smoothing filter is implemented directly on the spectral element mesh, for preconditioning FWI by incorporating prior geological information such as coherent lengths, dip and azimuth angles. Numerical illustrations on Marmousi and SEAM II benchmarks illustrate the importance of each ingredient we have developed for making efficient and flexible elastic FWI for land applications.