Improved Green’s functions from seismic interferometry

Under certain theoretical assumptions, the theory of seismic interferometry allows the construction of artificial (or virtual) sources and receivers at the locations of receivers in a physical experiment. This is done by redatuming the physical sources to be at the locations of the physical receivers. Each redatumed trace is formed by stacking the cross-correlations of appropriate recorded traces from each physical shot. For the resulting stacked traces to be a valid approximation certain requirements, like an adequate number of surface sources with a small enough spacing in the acquisition geometry, must be met. If these requirements are not met, the resulting virtual shot gather will contain artifacts. In this paper, we analyze both the sets of correlated traces (correlograms) and their stack. We observe that it is possible to reduce certain artifacts in the stacked traces by novel filtering operations. These filtering operations may have broad utility in all of seismic interferometric applications. 1