Abstract：Starting from 3-D acoustic equation and by introducing reference velocity,the paper deduced formulae of refraction item,and diffraction item and optimized and expanded the later,finally prestack depth migration equation of VSP data and its difference form adapting to any condition of variable velocity has been obtained.Error compensation of finite-difference algorithm and condition of wavefield imaging has been discussed in the paper.In a certain imaging condition and based on linear stack principle on wavefield propagation,the complete seismic imaging technique-stereoscopic seismic imaging that migrates surface seismic record,VSP record and cross-hole record into same imaging space has been proposed.The nature of stereoscopic seismic imaging is that imaging process of surface seismic data,VSP data and reflected seismic data in the hole can be unified a prestack depth migration process of wave equation and imaging resolution of each data can output independently at the same time.The results of model test show that due to different illuminant scope on object by each survey in process of stereoscopic seismic imaging,the image of geologic object can be strengthened and compensated and becomes more subtle.
