Analysing the effects of least-squares datuming on VSP multiple imaging

Interferometric transformations are widely applied to transform seismic data from one acquisition geometry to another. We used a correlation-type interferometric transformation to redatum verticalseismic-profiling multiples into surface-seismic virtual primaries. Conventional redatuming, based on the cross-correlation of seismic traces, yields virtual surface-seismic records that suffer from correlation artefacts, wavelet distortion, and low-temporal resolution. These effects are mainly caused by the limited recording aperture, the band-limited nature of the source wavelet, and the coarse source-receiver sampling. Least-squares migration of the virtual surface-seismic gathers can partially enhance the seismic resolution and improve the quality of the final migrated sections. However, our results demonstrate that the leastsquares datuming step remarkably helps suppress the cross-correlation artefacts, enhance the seismic resolution of the seismic events, and correctly deconvolve the source wavelet. Therefore, the obtained migrated sections suggest that least-squares datuming can be an essential processing step to apply to VSP surface-related multiples prior to imaging subsurface structures.