Geophysical monitoring of the Weyburn CO2 flood: Results during 10 years of injection

CO2 monitoring activities within the IEA GHG Weyburn-Midale CO2 Monitoring and Storage Project have been ongoing since 2000. Time-lapse seismic data provide the primary geophysical monitoring tool supplemented by passive microseismic monitoring. Here, we highlight results from seismic monitoring and the analysis methods applied to these data. Formal inversion methods (both prestack seismic inversion and model-based stochastic inversion) are being applied to optimize the geological model used to predict the storage behaviour of the reservoir. Seismic amplitude versus offset and azimuth analysis has been applied to identify areas of the caprock that may contain vertical fractures. Injection-related deformation of the reservoir zone has been modelled using coupled fluid flow-geomechanical modeling constrained by the observed low levels of microseismicity. Finally, we present results from a feasibility study on the use of electrical resistivity tomography for CO2 monitoring at Weyburn using existing steel well casings as electrodes. (C) 2011 Published by Elsevier Ltd.