Azimuth-opening angle domain imaging in 3D Gaussian beam depth migration

摘要

Common-image gathers indexed by opening angle and azimuth at imaging points in 3D situations are the key inputs for amplitude-variation-with-angle and velocity analysis by tomography. The Gaussian beam depth migration, propagating each ray by a Gaussian beam form and summing the contributions from all the individual beams to produce the wavefield, can overcome the multipath problem, image steep reflectors and, even more important, provide a convenient and efficient strategy to extract azimuth-opening angle domain common-image gathers (ADCIGs) in 3D seismic imaging. We present a method for computing azimuth and opening angle at imaging points to output 3D ADCIGs by computing the source and receiver wavefield direction vectors which are restricted in the effective region of the corresponding Gaussian beams. In this paper, the basic principle of Gaussian beam migration (GBM) is briefly introduced; the technology and strategy to yield ADCIGs by GBM are analyzed. Numerical tests and field data application demonstrate that the azimuth-opening angle domain imaging method in 3D Gaussian beam depth migration is effective.