InSAR Observations and Modeling of Anthropogenic Surface Deformation in the Alberta Oil Sands

Recent Interferometric Synthetic Aperture Radar (InSAR) observations over northern Alberta, Canada show persistent surface uplift occurring at rates of 1-4 cm/year, localized at several sites where the Steam-Assisted Gravity Drainage (SAGD) technique is currently being used to extract bitumen from the Athabasca oil sands. We find that uplift rates above the horizontal injector wells are strongly correlated with rates of steam injection, even though there is a net fluid loss from the reservoir pore space as oil and water are withdrawn through the production wells. In combination with available steam injection and bitumen production data at four sites, we use numerical reservoir flow models to explain how the thermal and geomechanical effects of steam injection on an oil sand reservoir can generate uplift at the surface. Results of our numerical experiments show that persistent surface heave consistent with observed rates can be driven by stress changes in the reservoir due to porous flow and thermal expansion.