Accurate monitoring of the ground deformation of a field under cyclic steam stimulation (CSS) can be used to calibrate predictive models, show the effectiveness of steam injection, and demonstrate the effect of the recovery operation on the surface elevation. Interferometric synthetic aperture radar (InSAR) uses radar returns from the ground to calculate highly precise estimates of the ground change. The authors discuss a new way of extracting deformation information from radar imagery, contributing to improved accuracy of InSAR surface-elevation monitoring.
The challenge in the Canadian oil sands is to achieve robust measurements with limited infrastructure. Essentially, the problem is to develop robust measurements of the ground movement without reliance on buildings, pipelines, or even installed targets [such as corner reflectors (CRs)]. The case study described here shows exceptional results for monitoring of regions without traditional point targets.
The operations and mechanism of thermal recovery of steam-assisted gravity drainage (SAGD) and CSS differ. SAGD is a continuous process of balanced injection and production, while CSS is a cyclic process of injection, soaking, and depletion. The methodology provided depends on an understanding of the expected ground movement but does not rely on foreknowledge of the motion itself. The rate of change in ground deformation associated with a CSS operation is key to the extraction of the signal (deformation) over the time required for this monitoring. The relatively short time scales and the high magnitude of the changes experienced in CSS are well-suited to the nontraditional methods described here.
The methods are validated by measurements of surface elevation by use of real-time kinematic (RTK) global-positioning-system (GPS) surveys acquired in the Primrose field coincident to the InSAR observations. The net-over-injection (NOI) metric provided by Canadian Natural Resources Limited (CNRL) is also used to demonstrate the causal relationship between injection and production volumes and the observed ground heave and subsidence, respectively.
Satellite Monitoring of Cyclic-Steam Stimulation Without Corner Reflectors
01 September 2017