Amplitude Variation with Offset Responses Modeling Study of Walkaway Vertical Seismic Profile Data at CO2 Geological Storage Site, Ketzin, Germany |
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| Authors: | YANG Can Sayed Hesammoddin KAZEMEINI FAN Wenfang Christopher JUHLIN and LIU Dameng |
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| Institution: | 1 China University of Geosciences, Beijing 100083, China; 2 Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; 3 Department of Geosciences, University of Bremen, Bremen 28334, Germany,1 China University of Geosciences, Beijing 100083, China; 2 Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; 3 Department of Geosciences, University of Bremen, Bremen 28334, Germany,1 China University of Geosciences, Beijing 100083, China; 2 Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; 3 Department of Geosciences, University of Bremen, Bremen 28334, Germany,1 China University of Geosciences, Beijing 100083, China; 2 Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; 3 Department of Geosciences, University of Bremen, Bremen 28334, Germany and 1 China University of Geosciences, Beijing 100083, China; 2 Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; 3 Department of Geosciences, University of Bremen, Bremen 28334, Germany |
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| Abstract: | An important component of any CO2 sequestration project is seismic monitoring for tracking changes in subsurface physical properties, such as velocity and density. Different reservoirs have different amplitude variation with offset (AVO) responses, which can define underground conditions. In the present paper we investigate walkaway vertical seismic profile (VSP) AVO response to CO2 injection at the Ketzin site, the first European onshore CO2 sequestration pilot study dealing with research on geological storage of CO2. First, we performed rock physics analysis to evaluate the effect of injected CO2 on seismic velocity using the Biot-Gassmann equation. On the basis of this model, the seismic response for different CO2 injection saturation was studied using ray tracing modeling. We then created synthetic walkaway VSP data, which we then processed. In contrast, synthetic seismic traces were created from borehole data. Finally, we found that the amplitude of CO2 injected sand layer with different gas saturations were increased with the offset when compared with the original brine target layer. This is the typical class III AVO anomaly for gas sand layer. The AVO responses matched the synthetic seismic traces very well. Therefore, walkaway VSP AVO response can monitor CO2 distribution in the Ketzin area. |
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| Keywords: | CO2 injection rock physics amplitude variation with offset walkaway vertical seismic profile seismic modeling |
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