Satellite SAR Interferometry (InSAR) has been widely used in recent decades to monitor earth surface displacements. Changes at ground surface level can be detected by simply comparing subsequent measurements of the satellite to ground distance. Although the basic idea is quite simple, the development of reliable InSAR algorithms was a long process as significant noise effects due to atmospheric phase delay and decorrelation phenomena had to be resolved. In 1999, the first results of the so- called Permanent Scatterer technique (PSInSAR), enabling the estimation and removal of atmospheric effects exploiting long temporal series of SAR acquisitions, was presented by the SAR group of Politecnico di Milano technical university. This approach meant moving from qualitative aerial information (InSAR) to quantitative information on a selected set of points (permanent/persistent scatterers) could be achieved, each measured to millimeter precision.
Further improvement in processing algorithms (i.e. SqueeSAR technique) have enhanced the spatial density of measurement points (Permanent Scatterers and Distributed Scatterers) also providing more effective filtering of the atmospheric artifacts. The availability of new high resolution satellites (i.e. COSMO-SkyMed and TerraSAR-X) has recently improved the monitoring capabilities up to monthly or weekly updates.
Thanks to the capability of providing high precision and high areal density surface displacement measurements over long periods of time Advanced InSAR technology represents one of the most valuable and cost-effective techniques for precisely monitoring surface deformation over hydrocarbon exploitation areas.
Volumetric changes in reservoirs due to fluid extraction and injection can induce surface deformations, which can highlight phenomena such as reservoir compartmentalization and fault reactivation. Monitoring such deformation can lead to a better understanding of the reservoir dynamics and can also provide valuable constraints for modeling reservoir behavior with the final goal of improving recovery factors.
Selected case studies in the Middle East and Caspian area are presented to highlight the effectiveness of advanced satellite Interferometry in reservoir monitoring, supporting the identification of fault-bounded reservoir compartments, the calibration of hydrocarbon reservoir geo-mechanical models and reservoir exploitation strategies.