QUANTIFICATION OF CO2 MASS INJECTED AT KETZIN USING 3D TIME-LAPSE SEISMIC DATA AND MULTIPHASE FLOW MODELING

The Ketzin CO2 storage site provides the experimental infrastructure to test established and new geophysical methods related to geological storage of CO2. CO2 is being injected and monitored using various methods. By now about 50,000 tons of CO2 had been injected into the Stuttgart Formation at approximately 650 m depth. Among the wide range of monitoring methods being applied at Ketzin, 3D time-lapse reflection seismic surveys comprise an important component. The first repeat 3D survey was acquired in Autumn 2009 after about 22000 tons of CO2 had

been injected. The time-lapse signatures of this CO2 can be clearly observed within a radius of about 300 m from the injection well with this method. Results of seismic interpretation are illustrated with synthetic seismic modeling and reservoir flow simulation of the migrating CO2. A multiphase flow modeling has been performed and synthetic seismic data are being generated based on the fluid flow simulation. Synthetic seismic modeling shows that the negative seismic impedance contrast between the shale and sandstone becomes stronger, when CO2 is present. The velocity push-down effect is observed in the field data as well as in the synthetic seismic data. Mass quantification of the injected CO2 visible in 3D time-lapse seismic data has been provided using results of multiphase flow modeling with a satisfactory match (more than 90%).