Elastic gaussian beam imaging of walk-away VSP data.

The approach to true amplitude seismic imaging for walk-away Vertical Seismic Profile (VSP) multi component data is presented and discussed. This approach is migration procedure based on weighted summation of prestack data. True amplitude weights are computed with application of Gaussian beams (GB). The couple of beams is used in order to compute true amplitude selective image of the rapid velocity variation. The total true amplitude image is constructed by superposition of selective ones being computed for a range of available dip angles. Shooting from the bottom overcomes difficulties due to multi arrivals of seismic energy which are common for complicated velocity models (in particular salt intrusions). In addition, the global regularity of Gaussian beams permits one not take care of, is the ray field regular or not. The use of P- and S-wave Gaussian beams provides the possibility to handle raw multi component data without of their preliminary separation to PP and PS waves. The true amplitude selective images computed for a variety of opening angles gives possibility to implement AVO analysis.