Active and Passive Seismic Imaging and Monitoring of CO2 Storage Sites in Germany

Some of the recent work on active and passive seimic imaging and monitoring in the frame of CCS related projects in Germany is summarized here. It comprises mainly results obtained by a site-independent feasibility study in which the benefits of advanced seismic imaging techniques are described. The recent development of advanced seismic imaging and inversion techniques directly suggests their exploitation in order to achieve these aims. We present one of these developments, 3D Fresnel-Volume-Migration (FVM). This technique is an extension of Kirchhoff-Prestack-Depth-Migration (KPSDM) and restricts the smearing of the wavefield along two-way-traveltime isochrons to the actual reflection/diffraction point using the concept of Fresnel volumes. The necessary information to perform this restriction is the emergence angle at the receiver, which is obtained from local slowness estimates using slant-stack or cross-correlation techniques. The method has been applied to the 3D SEG/EAGE salt model data set as well as a real 3D seismic data set from a potential CO2 storage site. The results show that FVM yields images of superior quality compared to KPSDM, both in terms of resolution as well as the suppression of artefacts. Therefore the quality of the resulting FVM images provide an excellent basis for further studies with respect to reservoir assessment and monitoring. Furthermore, some of the planned investigations in the frame of other large-scale demonstration projects in Germany are summarized and preliminary results of pre-injection studies with regard to pre-site characterization using active and passive seismic techniques are presented.