Abstract: What was described in this paper is the upgoing events of P and PSVwave on three components offset VSP records were separated by dint of the technique of polarization projection . By doing so,the record with the maximum energy of these two kinds (namely,the P and the PSV waves) of upgoing events was obtained. The VSP CDPS data were migrated bv using the paraxial raypaths technique, hence, the "bow ties" were thus cancelled. The lateral variation of the sand body in gas bearing formation for a certain well would be made clear by comparing the CDPS section of the P and PSV upgoing events obtained from the same well.