COMMON ANGLE IMAGE GATHERS OBTAINED FROM GABOR-DAUBECHIES BEAMLET PRESTACK DEPTH MIGRATION
基于GaborDaubechies小波束叠前深度偏移的角度域共成像道集

Due to multi-paths of wave propagating through complex media, the problem of reflector location ambiguity is often encountered in the conventional offset-domain common image gathers (CIGs). Angle-domain CIGs have been proposed as a solution to this problem and become a natural choice for velocity analysis, AVA and true amplitude migration/imaging. The development of wave-theory based seismic migration and imaging methods provides reliable ways for the construction of angle-domain CIGs of high quality. In particular, the beamlet-domain wavefield extrapolation and migration method, in which both the wavefield decomposition functions and the extrapolation propagators bear localization properties in both space and direction, has been proved to be an effective tool for angle-related studies. In this paper, beamlet prestack depth migration based on Gabor-Daubechies frame decomposition is used for angle-domain imaging. Through different stack procedures, both common reflection-angle image gathers (CRAIG) and common dip-angle image gathers (CDAIG) are constructed from the local angle image matrices. As a numerical example, the CRAIGs and CDAIGs for the SEG-EAGE 2D salt model are calculated and analyzed. Based on their distinct features, the applications of these two CIGs to seismic imaging are discussed in detail.