Geomechanic Interferometry: Theory and Application to Time-Lapse InSAR Data for Separating Displacement Signal Between Overburden and Reservoir Sources

Interferometric synthetic aperture radar (InSAR) data provides a measurement of the Earth's surface displacements to monitor reservoir stresses, fluid pressure and volume changes. However, the InSAR measurements may suffer from poor sensitivity and resolution. To improve the sensitivity of the InSAR data and localize the effects of the near-surface overburden, we employ a Green's function retrieval (GFR) approach that uses time-lapse InSAR data. In this work, we derive the equations and compute the sensitivity between InSAR displacements caused by the reservoir changes with respect to observation points (i.e., virtual sources) at the surface. We present this method with time-lapse InSAR data from an oil field in the San-Joaquin Valley to demonstrate improved resolution of the GFR-InSAR measurements for subsurface imaging and continuous reservoir monitoring with applications to development, production, and subsurface integrity.