POSTSTACK GAUSSIAN BEAM DEPTH MIGRATION

For Gaussian beam depth migration, the conventional kinematic ray tracing process is performed to find some ray paths from each surface source point. These ray paths serve as frames for wave propagation. The frequency components of the surface seismogram are then backprojected into the background velocity model as Gaussian beams. This process is accomplished by dynamic ray tracing along the previously found ray paths to obtain solutions to the local parabolic wave equation. The solutions are called Gaussian beams.

For depth migration of zero-offset stack section, the reflectivity image is that of the wavefield at time t=0 when all the reflectors explode; it is produced by evaluating Equation (17) at time t=0. Gaussian beam depth migration is accomplished by superposition of all Gaussian beams from all surface point sources, seismograms, to obtain the earth reflectivity image. The superposition of Gaussian beams is justified by the linearity of the wave equation and the wave phenomenon.