Seismic modeling for P-P and P-SV AVO analysis

Taiwen Chen, Donald C. Lawton

Seismic physical and numerical modeling experiments were undertaken in order to compare amplitude versus offset (AVO) responses for P-P and P-SV data collected over simple 2- and 3-layer models. Generally, the physical modeling and numerical modeling results agree rather well. It is clear that increasing the acoustic impedance difference between the overlying and underlying layers increases P-wave reflection amplitudes for the top of the second layer, and decrease the P-wave reflection amplitude for the bottom of the second layer. When the Poisson's ratio of the underlying medium is the same as that of the overlying medium, the P-wave amplitude decreases with increasing offset for both the top and the bottom of the second layer. For the converted wave, it seems that increasing the shear wave velocity for the underlying medium increases the P-SV reflection amplitude for the top of the second layer, and decreases it for the bottom. Besides, this study shows that there is an interesting possibility for recording P-P reflections with a radial-component receiver in areas with a high-velocity surface layer. Current modeling experiments are derived at examining the effect of a high-velocity surface layer on the AVO response of deeper reflectors.