Application Of Seismic Interferometry With Non-Physical Reflections Using Near-Surface Seismic Field Data

Seismic interferometry (SI) is a method that retrieves new seismic traces from the cross-correlation of existing traces, where one of the receivers acts as a virtual seismic source whose response is retrieved at other receivers. When using sources only at the surface, and the so-called one-sided illumination of the receivers occurs, we will retrieve not only the desired physical reflections but also non-physical (ghost) reflections. These non-physical reflections appear due to waves that propagate inside a subsurface layer. Thus, they contain information about the seismic properties of the specific layer. We illustrate the technique’s potential using numerically modelled data for a subsurface model with a low-velocity layer, which is also pinching out, and near-surface field data. We apply SI by cross-correlation and auto-correlation. Both resulting non-physical reflections are sensitive to the physical rock properties of the layer that causes them to appear in the SI results. Moreover, non-physical reflections in zero-offset gathers that result from SI by auto-correlation show very good conformity with the geometry of the subsurface layers.