Nonrepeatability effects on time-lapse elastic full-waveform inversion for VSP seismic data

Xin Fu, Kristopher A. Innanen, Scott Keating, Qi Hu

In this study, we investigate non-repeatability effects on time-lapse elastic full-waveform inversion for VSP (vertical seismic profile) seismic data. The non-repeatabilities tested are the non-repeatability on source locations, the non-repeatability on random noises, and the non-repeatability on the near-surface properties. Four time-lapse inversion strategies, including the parallel strategy (PRS), the sequential strategy (SQS), the double-difference strategy (DDS), and the common-model strategy (CMS, are applied in each type of non-repeatability. From the investigation, we can conclude: P-wave velocity changes can be better recovered than S-wave velocity changes; except for the DDS, the other three strategies have similar performance; the DDS also has similar performance to the others when acquisition geometries for baseline and monitor surveys are identical, but it is sensitive to the non-repeatability on source locations between twice surveys; no strategies can effectively handle the case of random noise; near-surface property changes have limit impact on the recovery of time-lapse changes for VSP data.