2D nonlinear inversion of walkaway data
Seminar Room 1, Newton Institute
Well-seismic data such as vertical seismic profiles (VSP) provides detailed information about the elastic properties of the subsurface at the vicinity of the well. Heterogeneity of sedimentary terrains can lead to non negligible multiple scattering, one of the manifestations of the non linearity involved in the mapping between elastic parameters and seismic data. Unfortunately this technique is severely hampered by the 1D assumption.
We present a 2D extension of the 1D nonlinear inversion technique in the context of acoustic wave propagation. In the case of a subsurface with gentle lateral variations, we propose a regularization technique which aims at ensuring the stability of the inversion in a context where the recorded seismic waves provide a very poor illumination of the subsurface. We deal with a huge size nonlinear inverse problem. Solving this difficult problem is rewarded by a vertical resolution much higher than the one obtained by standard seismic imaging techniques at distances of about one hundred meters from the well.