Abstract: To enhance the imaging precision of complex fault blocks and carry on fine description of small complex fault blocks, the key is to increase the density and precision of velocity analysis. Through actual data processing analysis, 2% of the imgration velocity error will exert obvious effect on the intended interval migration imaging results during the application of prestack time migration to imaging of complex fault blocks. Therefore, improving the accuracy of velocity analysis is the key to high-precision seismic imaging. The conventional velocity analysis method is used hyperbolic NMO formula to carry on velocity analysis, and manual pick-up velocity is needed to be used. So the density is restricted, the quality of velocity analysis is also influenced by human factors greatly. In addition, as a result of the anisotropic characteristics underground media, reflecting the travel time is no longer a hyperbola, the application of conventional hyperbolic NMO may lead to uneven correction in the far-offset. In is paper, the high-density anisotropic velocity analysis method is proposed to be used. High-density automatic velocity analysis may be conducted, so non-hyperbolic NMO problems caused by anisotropy could be solved.

Key words: high-precision 3D seismics, prestack migration, high-density velocity analysis, Dongpu sag