Velocity model building — key issue for seismic migration process

Summary Prestack Kirchhoff Time Migration (PSTM) is probably the most used method for obtaining proper image of complex subsurface. In areas of rapid lateral and vertical velocity changes, energy is dispersed in such a way that it is very complicated to be provide desired resolution of the data. The PSTM focuses scattered energy by moving it to a proper subsurface position if accurate velocity model is provided for migration. Only when energy is properly focused, stacking improves the quality of signals and eliminates noise. Building such velocity model, can bring significant improvement of seismic data quality (both resolution and continuity) and proper spatial structural positioning. For these reasons, velocity estimation process has great influence in seismic imaging. The process of moving seismic events to their actual location of occurrence in the subsurface is strongly dependant on the velocity model, but also is greatly affected of the whole processing quality. Seismic processing is long and comprehensive process of converting seismic field data into a meaningful seismic section and involves a lot of steps of data manipulations. The result is a high quality time image of the subsurface which better matches to the real geologic structures.