The Virtual Source Method ? Verifying the concept using numerical and physical modelling

Abstract

The Virtual Source Method (VSM) has been proposed for removing the effects caused by heterogeneities in the near surface. The method involves acquisition geometries similar to that of VSP, with receivers below the most troublesome part of the overburden. The time reversal principal is utilised to focus down-going energy through the overburden into useful primary energy at the virtual source location. The time reversal process is performed during data processing, and requires no knowledge of the velocity model between sources and sub-surface receivers. The result is a downward continued-dataset with virtual sources at the sub-surface receiver locations. The concept is verified using numerical and physical modelling, which demonstrates that the method can be used to accurately detect reflectors at depth, where conventional seismic fails.