Abstract：The precision of velocity is directly relative to the quality of stack and migration of seismic data in 3D deep seismic exploration.Faced with the characteristics of weak reflected energy,poor S/N ratio,lower resolution and smeared base reflections in deep seismic data,the paper discussed the uncertain factors in analysis of deep seismic velocity according to basic theory of seismic exploration.It is considered that it must consider the isotropic medium as VTI medium in a deep condition and the time-distance curves at larger offsets are no longer the hyperbolic curves but high-order curves contrarily.Therefore,the common-used velocity analysis method is no longer used and new velocity analysis method is needed when carrying out velocity analysis.The paper recommended two methods for velocity analysis in VTI medium:non-hyperbolic P-wave velocity analysis and template method,which achieved practical and stable effects.
