Fundamentals of Heat Transport at the Edge of Steam Chambers in Cyclic Steam Stimulation and Steam-assisted Gravity Drainage

Abstract Currently, large-scale commercial in-situ recovery of bitumen from oil sands reservoirs is done by thermal gravity drainage oil sands recovery processes such as cyclic steam stimulation (CSS) and steam-assisted gravity drainage (SAGD). In these processes, steam is injected into the formation, which then heats bitumen until it is sufficiently mobile enough to be moved to the production well. The key goal of these processes is controlled and targeted steam delivery, really heat delivery, to the reservoir, and thus, both heat transfer and consequent bitumen mobilization are key controls on the performance of the processes. Here, we describe conductive and convective heat transfer at the edge of steam chambers and oil mobilization just beyond the edge of the chamber. The results demonstrate the complex interplay between heat transfer and oil mobilization: heat transfer controls the temperature profile beyond the edge of the steam chamber, which sets the oil viscosity profile, which in turn controls bitumen mobilization. Relative permeability, geomechanics, and geologic heterogeneity make the phenomena more complex. The discussion suggests that self-corrective robust recovery processes or dynamic well interventions such as smart wells that yield uniform steam chambers are required to ensure efficient heat transfer and oil mobilization.