Abstract

P-SV reflections are generated by a compressional-wave source and result from P waves that are converted to shear (SV) waves upon reflection. Recording both the P and SV components yields compressional and shear data simultaneously. Verifying that the easily detected events really are P-SV reflections is accomplished by noting the good correlation of surface CDP data with vertical seismic profile (VSP) reflections. Stacking velocities from P-SV CDP gathers determine the V p V s product when source-to-receiver offset is less than the depth of the reflector but data from synthetic models show that P-SV reflections are nonhyperbolic for shallow reflections or when source-to-receiver offset is too large.Shear velocity (V s ) can be calculated from P-SV reflections by one of two techniques: comparison of stacked section P-P and P-SV reflection times or by using the P-P and P-SV stacking velocities. Unfortunately, most P-SC reflections on a P-SV seismic section do not necessarily originate from exactly the same depth as P-P reflections. When this depth discrepancy occurs, the reflection-time comparison technique fails. In addition, V s cannot be calculated from P-SV reflections, and we must settle for the V p V s product from P-SV reflection stacking velocities. When P-SV stacking velocities are input to the familiar Dix equation, the resulting interval velocities yield the V p V s product.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview