Applications of virtual refraction in time‐lapse monitoring

Abstract

The virtual source method (VSM) enables imaging and monitoring below complex heterogeneous overburden. This can be accomplished by correlating the wavefields due to surface shots recorded by downhole geophones. In order to extract the true impulse response between the geophones, the VSM requires summation of the correlated wavefield over continuously distributed shots surrounding the geophones. In practice, such a source distribution is not achievable and hence leads to spurious events in the virtual source data. Here we demonstrate the benefits of using one such spurious arrival: “virtual refraction” for the time‐lapse monitoring.