Seismic and Surface Deformation: Insights from Qualitative Comparisons over a SAGD Reservoir in Alberta

Interferometric Synthetic Aperture Radar (InSAR) is becoming a more desirable method to monitor surface deformation, in particular, ground heave in the oilsands related to thermal SAGD operations. Devon had licensed data from TRE-Altamira using the RADARSAT-2 satellite, which collects roughly 9 usable images each year to calculate deformation. Surface deformation has been used to monitor pressure changes in conventional reservoirs and carbon sequestration and is primarily thought as a method to understand and monitor caprock integrity in oilsands production. Previous efforts (Granda et al, 2012) have shown that surface deformation can be correlated with steam injection rates. Others (James et al, 2012) have also shown that surface deformation can be used to map the steam chamber. However, there are discrepancies when surface deformation is used to infer steam chamber thickness. These differences can provide further insight into reservoir conformance, production, and quality.

Although surface deformation and seismic time delays are both results of thermal SAGD operations—Steam injection results in fluid substitution, thermal expansion, and increased pressure—are their measurements impacted differently, and how so? Surface deformation is driven by thermal expansion & pressure increases and seismic time delay by fluid substitution. This qualitative interpretation of these observations can grant us further insight into the quality of the reservoir we are producing, pad conformance and allow us to characterize different styles of low performing reservoirs. We may also be able to infer the degree of depletion by using the surface deformation growth curve. Understanding the potential surface deformation we will help us to mitigate risk against damaging current production infrastructure and facilities.