Monitoring is also required to assess whole reservoir performance. Time-lapse 3D and 4D
seismic surveys have been successfully employed to image the underground CO2 (Arts et al.
2002, Chadwick et al. 2005). These studies were able to monitor the known injected amounts
of CO2, however, some aspects of reservoir structure and properties remained imperfectly understood and thus they could not provide a unique verification of complete reservoir behaviour (Chadwich et al., 2006). Recent studies (Chadwich et al., 2006) assessed the key aspects of the seismic data that constrain models of CO2 migration through the reservoir. These key aspects of the seismic data comprise derivation of layer thicknesses from seismic amplitudes data (tuning), topographic analysis of the reservoir top versus CO2 - water contact (static ponding), and thickness determination from combinations of the amplitudes and the structural analysis (Chadwich et al., 2006). This study show that the topmost layer of the CO2