Место издания: London , Год издания: 2007

The approach to true amplitude seismic imaging for walk-away Vertical Seismic Profile (VSP) data is presented and discussed. This approach can be treated as migration procedure based on weighted summation of pre-stack data. True-amplitude weights are computed with application of Gaussian beams (GB). In contrast to common approach to GB pre-stack migration (see, for example, (Hill, 2001)) we do not use these beams for composition of Green's function. Instead we shoot a couple of properly chosen GB with fixed dip and opening angle from the current imaging point towards acquisition system. The use of these couple of beams provides true amplitude selective image of the rapid velocity variation within a target area. The total true amplitude image is constructed by superposition of selective images computed for a range of available dip angles. In order to estimate this range we perform preliminary survey design. Shooting from the bottom overcomes difficulties due to multi arrivals of seismic energy being common for complicated velocity models (salt intrusions), while global regularity of Gaussian beams permits to avoid any troubles due to the possible singularities of the ray field. Numerical experiments with synthetic data (Sigsbee2a) are presented and discussed.