Seismic Modeling of the AVO/AVA Response to CO2 Injection at the Ketzin Site, Germany

Over 64 kilotons of CO2 have been injected (May, 2013) into a heterogeneous sandstone reservoir (saline aquifer) at 630-650 m depth. 4D seismics have been applied to monitor CO2 at the Ketzin site. However, the obtained time-lapse seismic signals have been so far interpreted as being caused by fluid saturation changes only. Modeling of the AVO/AVA response allows us to study two kinds of effects: CO2-saturation- and pore-pressure-related effects. Our results indicate that it is rather infeasible to discriminate between both these effects at the Ketzin site dealing with the real seismic data with limited signal/noise ratios.