| dc.description.abstract |
Prestack depth migration for seismic reflection data is currently one of the powerful tools for imaging complex geological structures such as salt domes, faults thrust belts, and stratigraphy structures. Since the subsurface structure generally consists of anisotropic media, when we apply migration to seismic reflection data without considering it in large magnitude anisotropic media, it may lead to migration error. Here we present a result of the prestack depth migration in anisotropic media using Split-Step-Fourier (SSF) method. SSF method, which is the one of wavefield extrapolation migration in frequency-wavenumber domain, is usually to apply migration to seismic reflection in post-stack isotropic media when the lateral velocity variations are small. When we apply this to anisotropic problem, we should define velocities that depend on incidence angles and compute vertical wavenumber. Here we use vertical wavenumber which is directly calculated by the analytical solution of the Christoffel equation instead of using reference velocity. According to the numerical model test for a simple geological model including anticline and syncline, the prestack depth migration using SSF method in weak anisotropic media shows the subsurface image is similar to the true geological model. The anisotropic phase-shift-plus-interpolation (PSPI) is well known that the reference wavefield is computed for each pair of anisotropic parameters, Thomsen's parameters, in order to consider anisotropic problem. However, the anisotropic SSF directly use variations of Thomsen's parameters using the solution of Christoffel equation. |
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