Elastic anisotropic finite-difference full-wave modeling and imaging of the tilted transversely isotropic (TTI) media

Abstract

Imaging below the tilted transversely isotropic (TTI) media poses serious problems and distortions in the image, which is very common with imaging subsurface geological targets for hydrocarbon exploration in the fold-thrust belts or active tectonic areas. To model and image below the TTI media having symmetry axis orthogonal to the dipping anisotropic layers, a TTI thrust sheet is considered for elastic anisotropic finite-difference full-wave modeling to generate synthetic seismic data using staggered grid scheme of wave propagation. Free surface conditions at the top and absorbing boundary conditions for other three sides of the model have been imposed to reduce undesirable edge effects and suppress dispersions. The synthetic data generated are migrated using the Kirchhoff pre-stack depth migration (PSDM) technique followed by migration velocity analysis (MVA) algorithm with traveltime computations using anisotropic ray-tracing technique for the model to image below the TTI thrust sheet. The MVA algorithm adopted also estimates the final inversion parameters of the model showing flattening of the reflected events in the image gathers and is a powerful tool to handle tilts more than 60° without much distortions of the image gathers.