Locating near-surface scatterers using non-physical scattered waves resulting from seismic interferometry

We use controlled-source seismic interferometry (SI) and inversion in a unique way to estimate the location of near-surface scatterers and a corner diffractor by using non-physical (ghost) scattered surface and body waves. The ghosts are arrivals obtained by SI due to insufficient destructive interference in the summation process of correlated responses from a boundary of enclosing sources. Only one source at the surface is sufficient to obtain the ghost scattered wavefield. We obtain ghost scattered waves for several virtual-source locations. To determine the location of the scatterer, we invert the obtained ghost traveltimes by solving the inverse problem. We demonstrate the method using scattered surface waves. We perform finite-difference numerical simulations of a near-surface scatterer starting with a very simple model and increase the complexity by including lateral inhomogeneity. Especially for the model with lateral variations, we show the effectiveness of the method and demonstrate the estimation of the subsurface location of a corner diffractor using S-waves. In all models we obtain very good estimations of the location of the scatterer. (C) 2013 Elsevier B.V. All rights reserved.