Monitoring CO2 Storage Using Seismic-interferometry Ghost Reflections

Time-lapse seismic monitoring is a fundamental part in most monitoring programmes involving CO2 storage. Even though the seismic method has proven its applicability for monitoring, there are two major causes of uncertainty in the estimation of changes in the reservoir properties: non-repeatability of the source positions and the difficulty in distinguishing the time-lapse effect due to the overburden from that of the changes taking place in a CO2 reservoir. We show that utilization of non-physical (ghost) reflections retrieved by seismic interferometry can address the two mentioned reasons of uncertainty. We apply this idea on numerically modelled data as well as on data from scaled laboratory experiment at ultrasonic frequencies.