Migration velocity analysis for anisotropic models

Migration velocity analysis for anisotropic models

Yunyue (Elita) Li and Biondo Biondi

Abstract:

Anisotropic models are recognized as more realistic representations of the subsurface in complex geological environments. These models are widely needed by many kinds of migration and interpretation schemes. However, anisotropic model building is still a challenging problem in the industry. In this paper, we propose an approach to building anisotropic models from surface seismic data based on the theory of Wave-Equation Migration Velocity Analysis (WEMVA). Because of the ambiguity between depth and Thomsen parameter $\delta$ , we parametrize our model space using only NMO velocity ($V_{nmo}$ ) and the anellipticity parameter $\eta$ . We tested the anisotropic WEMVA on a shallow part of the Hess synthetic VTI model. The results show that anisotropic WEMVA is effective in resolving some of the anisotropic perturbation. However, a unique solution to the inversion requires additional constraining information.