Use of ambient noise to enhance the low frequencies of seismic migration images

For seismic exploration (i.e. reservoir geophysics), retrieval of body waves appears promising, especially at low frequencies (below 3 Hz) where seismic vibrators reach a limit. These low frequencies are of interest for velocity model building (Baeten et al. 2013) and for broadband seismic inversion (Kneller et al. 2014). Here we demonstrate an example of body wave retrieval using ambient noise correlation in the context of seismic monitoring. The result of the ambient noise correlation is correctly arranged to produce noise-induced shot point gathers at each sensor positions. The noise-induced migrated image is compared and then combined with the image obtained by migrating the conventional active shot point gathers generated by vibroseismic sources (Cotton et al, 2014). In so doing, we considerably broaden the image spectrum toward the low frequencies.