Attenuation analysis for heterogeneous transversely isotropic media

Attenuation coefficients obtained from seismic data may provide sensitive attributes for reservoir characterization and increase the robustness of AVO (amplitude variation with offset) analysis. Here, we present an algorithm for ray tracing in attenuative anisotropic media based on the methodology of C̆ervený and Ps̆enc̆ik. Both kinematic and dynamic ray tracing are carried out in an elastic reference medium, with the attenuation terms incorporated as perturbations along the ray. Numerical examples for smoothly varying transversely isotropic (TI) media demonstrate the accuracy of the method. The dynamic ray-tracing technique provides an efficient forward-modeling operator that can be used in the inversion for anisotropic attenuation. We outline a methodology for estimating attenuation coefficients in 2D heterogeneous transversely isotropic (TI) media. A necessary prerequisite for accurate attenuation analysis is reconstruction of the heterogeneous velocity field. If the subsurface can be approximated by a piecewise-factorized VTI (TI with a vertical axis of symmetry) medium, the velocity model can be built using the migration velocity analysis algorithm proposed by Sarkar and Tsvankin. Attenuation coefficients in each factorized block can then be estimated using gradient-based inversion that employs dynamic ray tracing.