Spectral analysis of post-imaging seismic data

The seismic image represents the spatially variable reflectivity of the medium where migration effectively rotates the wavelet to be normal to the imaged reflectors. While this is the general case, it is often disregarded, and one-dimensional spectral analysis of the vertical coordinate is commonly used. We show that spectral processing of post-imaging data in the direction normal to the reflectors provides accurate results for steep and complex structures. We introduce the concept of Orthogonal-Image-Gathers (OIGs) which facilitate this approach while providing a platform for handling spatially variable spectral distortions due to the velocity field and other medium-related properties.