Research Of 3-D Seismic Prestack Depth Domain Imaging In Laterally Varying Media And Application

The conventional imaging methods in time domain can not fulfill requirements for complex geologic area, so we have to do depth domain imaging, especially doing 3-D prestack depth migration(PSDM). It is important to build velocity model as well as to select an appropriate imaging method . And both of them need massive computer resource, so the good processing routing is key in the 3-D prestack depth migration. It is showed to the character of every depth migrating method by analyzing the principle of prestack depth migration in this paper, and variable methods of building velocity model are searched. By the case of 3-D seismic exploring in laterally varying media, the building velocity model's idea and processing routing of 3-D PSDM is explained deeply. Finally a series of new and practiced methods about PSDM, building velocity model and optimizing computer resources are presented in this paper. The coherence of the migrating result and the well information shows that the theory and methods are practiced and efficient. It is beneficial in improving the application and development of 3-D PSDM in got good imaging effect.Firstly, many methods of prestak depth migration fitting complex geologic area are entirely introduced and briefly commented on in the paper , such as Kirchhoff integration migration , split-step Fourier migration , Fourier finite-difference migration , finite-difference migration in frequency-Wavenumber domain, pseudo-screen depth migration, wave-field extrapolation based on Born and Rytov approximation. And we put forward the application conditions of every depth migration method in the practice. These migration theory is beneficial to our research.Secondly, we bring forward a new , quickly and integrated method about building complex model after showing several currently popular methods of building model. It will suit variable complex area and is worthwhile .Thirdly, we design two complex structure models by using finite-difference simulation. The model's migrated result show the advance of depth migration as well as the difference between time migration and depth migration. Modeling can guide building model and help us do PSDM better.Finally, I think that PSDM is a system engineering of conjoined theory with practice tightly and every step directly affects imaging appreciation, we give 3-D prestack depth migration workflow in laterally varying media by the case. Because the final migration result is better consistent with the well, so I think that my depth migration workflow is reasonable and practiced.