Comparison of phase shift cascade and global matrix elastic wavefield modeling

Yanpeng Mi, Gary F. Margrave

An analysis of the spectral variation of the surface displacement and velocity fields caused by PP and PS modes in two types of models is presented. According to the generalized Otransmissivity should be attenuated by multiple scattering which occurs in finely layered media and the attenuation effect is also offset/angle dependent. By using geological models of different number of layers and thickness, we looked for this phenomenon in synthetic data in which interbed multiple reflections are taken into account. The geological models are derived from the well log from Blackfoot 09-08 and the synthetic seismograms are calculated using forward wavefield modeling by phase shift cascade (ELMO) and OSIRIS, a commercial forward modeling software based on the direct global matrix approach. Observation on the synthetic data shows that the effect of multiple scattering on the amplitude spectrum of displacement field is offset dependent. Its variation with the number of layers and the thickness of the layers is also observed. However, we did not observe an obvious attenuation effect over a certain bandwidth.