One of the most important steps in seismic processing data concerns to migration the seismic reflector. In the last years, we have seen several approaches used to build the migrated section and, simultaneously, to recover reflection coefficient values corrected for geometrical spreading loss, the so-called amplitude preserve migration or true-amplitude migration methods. This work aims at applying a true-amplitude depth migration algorithm in acoustic inhomogeneous media, with a constant gradient velocity function and considering a 2.5-D situation. The 2.5-D migration process is based on the Kirchhoff integral operator and the ray theory. It is performed essencially by a weighted diffraction stacking, with the diffraction traveltime curve given by the ray tracing equations tailored to constant gradient velocity. By choosing appropriate weight function used to stack the data, the result of the migration process is a measure of the reflection coefficient at the searched-for reflection point, that is function of the incidence angle. This is very usefull in other important process as amplitude-versus-offset (AVO) and amplitude-versus-angle (AVA) analysis. As any other depth migration process, it is necessary an accurated macro-velocity model, what means to know the velocity gradient. The algorithm was applied to synthetic seismic data generated by the ray software SEIS88 for two kinds of geophysical models. The results pointed out the precision and stability of the presented 2.5-D migration algorithm. It is available for recovering reflection coefficient measures and gives informations about lithological properties of the seismic reflectors. It is also important to note that this algorithm is not able to migrate in singular ray situations, as for example caustics or diffraction zones.
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