Time-lapse seismic surface and down-hole measurements for monitoring CO2 storage in the CO2SINK project (Ketzin, Germany)

Abstract

Ketzin is an European pilot site for onshore CO2 storage in a saline aquifer. Injection started in summer 2008 and to date, more than 37.000 tons of CO2 have been injected into the Stuttgart Formation at approximately 650 m depth. A wide range of monitoring methods are being applied at Ketzin, among which are active seismic observations at various scales. 3D reflection seismic, combined surface-downhole measurements and crosshole tomographic surveys were performed before injection and after the start of injection in order to image the reservoir and to track the CO2. Time-lapse signatures of the injected CO2 were observed by all active seismic methods. The CO2 could be detected by increased reflectivity at the top of the injection reservoir, by a change in the attenuation behaviour and also by reduced propagation velocity within the reservoir. The ongoing injection of CO2 during the next years will be followed by further repeat surveys. Current investigations focus on the still difficult problem of the quantification of the CO2 imaged by the geophysical measurements. © 2011 Published by Elsevier Ltd.