In the light of the geological conditions of the new exploration field abroad characterized by complexity,varying water depth,scarcity and uneven distribution of drill holes,and lack of velocity data,it is often difficult for conventional methods to carry out fine time depth conversion.In order to effectively detect the structure,this paper proposes using seismic data and the available well data to build virtual wells for quantitative characterization in no-well area.The reasonable construction of virtual wells can effectively reduce the uncertainty of the velocity field's establishment,ultimately improve the time-depth conversion accuracy of the study area,and lay a solid foundation for the optimization of traps and evaluation of favorable targets,so as to reduce the risk of exploration.Using the establishment of virtual well constrained velocity field,such a means provides a feasible choice of time depth conversion in the area characterized by no or few wells,remarkable varying water depth,and drastic stratigraphic change,thus effectively improving the accuracy of time-depth conversion.