Comparing virtual versus real crosswell surveys

Abstract

The virtual source method (VSM) is a useful tool for imaging below complex overburden and monitoring in the presence of time-varying overburden. This concept, when extended to crosswell geometry produces data comparable to real crosswell data. Using a field data example we demonstrate that virtual crosswell data is kinematically comparable to real crosswell data, but the virtual crosswell method possesses flexibilities, which are difficult to achieve in a real crosswell survey. Some of these flexibilities include the ability of the virtual source to radiate either horizontally or vertically and the possibility for the virtual source to radiate only Por only S-waves. It is also possible to create virtual crosswell data that contain only the direct arrivals or only the reflections. These features of the virtual crosswell method should make it useful for crosswell tomography, imaging and reservoir monitoring for moderate interwell distances.