Lawrence Berkeley National Laboratory

Geodetic monitoring involves the repeated measurement of the deformation of the Earth. As discussed here, it is a cost-effective approach for inferring reservoir integrity and detecting possible leakage associated with the geological storage of greenhouse gas emissions. Most geodetic methods have favorable temporal sampling, from minutes to months depending upon the technique adopted, and can detect anomalous behavior in a timely fashion. Satellite-based approaches such as Interferometric Synthetic Aperture Radar (InSAR), with their high spatial resolution and broad coverage, are particularly well suited for monitoring industrial-scale storage efforts. Multitemporal analysis, such as permanent scatterer techniques, are improving the accuracy of surface displacement measurements to better than 4 - 5 mm. New satellites, including the recent X-band systems, are allowing for the routine estimation of two components of deformation. Data interpretation and inversion techniques may be used to relate the observed displacements to injection-related volume change at depth. InSAR monitoring was used successfully at a gas storage site at In Salah, Algeria, where it was determined that the flow in the reservoir was influenced by large-scale fault/fracture zones. InSAR observations are also key components of the monitoring programs at the Aquistore CO2 storage project in Canada, and the Illinois Basis Decatur Project in the United States. Current InSAR data from both sites indicate no major surface deformation that might be attributed to the stored carbon dioxide, suggesting that the injected fluid remains at depth.