A West Africa Case History for Laterally Variable Anisotropic Velocity Model Building

A case history of anisotropic velocity model building on a West Africa offshore dataset is proposed. The goals of the project were to improve depth imaging, with accurate event placement and fault positioning, and to obtain the best velocity model for pore-pressure prediction. In order to obtain a robust and reliable estimation of the anisotropic parameters two independent methods were used: the first one, used as reference, is based on the standard time-domain approach whilst the second one works in depth-domain and applies the migration velocity analysis principles. In addition to anisotropy estimation, the velocity volume was refined with a grid tomography approach. The anisotropic parameters estimation from the two methodologies is coherent, and results in an improved quality of the subsurface image with respect to both PSTM and isotropic PSDM