CCS Monitoring by Inversion of Reservoir Pressure and Saturation Changes from Timelapse AVO Differences and Time-Shifts

Summary The main storage-related challenges for accelerated deployment of CCS are capacity, confidence and cost. These challenges are to be addressed by amongst others focusing on improving strategies for monitoring and management of the pore pressure distribution in the CO2 storage reservoir. Pressure-driven decision support protocols are to be developed for safe and cost-effective reservoir monitoring. These protocols will enable the operator to maximize CO2 storage capacity and quickly turn monitoring data which suggest non-conformance into plans for corrective actions. A new extended method is developed for inverting and de-noising reservoir pressure and water saturation changes from timelapse AVO differences and time-shifts for the purpose of CCS monitoring and conformance. Detailed reservoir pressure and saturation fronts are obtained for 4D data in the Norwegian offshore, honoring reservoir compartments and fault boundaries found in comparative studies. Application on a CCS candidate field offshore Norway is currently being researched in a synthetic study for purposes of benchmarking, pre-storage analysis, monitoring plans and conformance studies. If back-estimation of pressure and saturation changes is successful, the results for field data become substantially more credible and allow for 4D seismic history matching.