Abstract：The curvature effect of wave rays in vertically and horizontally-nonuniform medium must be considered in making joint tomography of interborehole seismic data and inverse VSP data. Desirable result can be achieved by performing dual-point ray tracing with the use of "target practice "method, solving for ill-conditioned equation with the aid of singular value decomposing, designing a theoretical model for test, and processing real interborehole seismic data and inverse VSP data according to this procedure. Ray tracing may result in blind zone in the case of complicated medium. In order to eliminate the trouble caused by the blind zone in inversion, we use straight-ray tracing over the blind zone instead of curved-ray tracing.
