f The generalized primary representation of 3D seismic data from highly heterogeneous media

In seismic modeling as well as in seismic imaging it is common use to ignore the rapid spatial variations of the medium parameters at a scale much smaller than the seismic wavelength. In particular, for 2-D or 3-D heterogeneous media the following approach is frequently used: - Replace the true medium by a 'macro model' that contains piecewise smoothly varying medium parameters and a 'contrast model' that is a spatially band-lirnited of the difference between the true medium and the macro model. - Formulate an implicit integral equation for the wave field in which the macro model describes the 'propagation effects' (in terms of Green's functions) and in which the contrast model describes the 'scattering effects'. - Solve this equation iteratively. This yields an explicit integral representation of the wave field that is non-linear in the contrast parameters.