Detection of Localized Surface Uplift by Differential SAR Interferometry at the Hangingstone Oil Sand Field, Alberta, Canada.

We estimated the surface uplift (heave) rate due to steam-assisted gravity drainage (SAGD) at the Hangingstone oil sand field in Alberta, Canada, by stacking differential synthetic aperture radar (SAR) interferograms. To improve accuracy, a Landsat-7 Enhanced Thematic Mapper Plus intensity image was coregistered with the SAR intensity image. We examined three interferogram filtering methods and identified one that provided the desired effect of light filtering in areas of low noise and heavier filtering in high-noise areas. Based on our analysis of interferogram coherences, site-specific decorrelation highly depends on local seasonal changes. Stacking was performed to estimate the surface uplift rate while removing atmospheric and seasonal effects. The amounts of the uplift rate and slope change estimated by means of InSAR analysis reached a maximum of 3.6 cm/yr and 0.003%, respectively, for the period of 2007-2008. Comparison of the magnitude and patterns of the estimated surface uplift demonstrated that the uplift estimated from InSAR analysis agrees well with that obtained by conventional geodetic (GPS) surveys from a network of 54 monuments. Surface slope changes due to SAGD that we detected by using InSAR over one year in this oil sand field were small, so destruction of surface facilities by uplift is unlikely in the short term. 

(a) Map of vertical displacement rate derived from stacking of un- wrapped differential interferograms. (b) Distribution of injection wells.