Abstract：We derive the expressions of both the time-distance curves of reflection waves in 2-D or 3-D VSP data and the coordinates of the minimal points. We also put forward the methods for analysing the distributions of VSP reflection points with the use of known parameters. Having systematically analysed how VSP reflection point distribution depends on interface depth, interface dip, offset, observation depth and source direction, we reveal the relationship between VSP reflection point distribution and the distribution of surface seismic common-shot reflection points, When applied in VSP observation system design in the case of dipping interface, this analysis result favours determining proper parameters. The application of this analysis result to real VSP data interpretatirn will help people to correctly locate VSP reflectionpoint image and to correctly correlate it with surface-seismic migration section.
