Conformance Control for SAGD Using Oil-in-Water Emulsions in Heterogeneous Oil Sands Reservoirs

Abstract Steam-Assisted Gravity Drainage (SAGD) is a widely used technology for heavy oil and bitumen recovery in Alberta, Canada. However, a SAGD conformance problem arises due to the heterogeneity of oil sands reservoirs, such as the presence of high permeability zones and high water saturation zones. In particular, during a geomechanical dilation start-up process that has been developed and applied in SAGD start-up operations, the dilation fluid tends to flow into the high permeability zones, leaving the low per-meability zones un-swept. Therefore, the high permeability zones must be temporarily and selectively blocked off so as to more effectively dilate the low permeability zones along a SAGD well-pair. Laboratory permeability reduction tests in sandpacks by oil-in-water (O/W) emulsion injection showed that a permeability reduction of up to 99.95% can be achieved. Results of emulsion injection in parallel-sandpack tests demonstrated that a good conformance control can be obtained by a suitable combinations of IFT, emulsion quality, emulsion slug size, and oil phase viscosity of an emulsion system. The reservoir simulation study was conducted to first match the laboratory test results and then to optimize SAGD conformance control operations by emulsion injection in heterogeneous oil sands reservoirs. A field-scale SAGD simulation model was established to show that emulsion injection during the dilation start-up process can build up communication between the injector and producer, resulting in better steam chamber growth and lower cumulative steam-oil-ratio (CSOR).