Abstract
A new heavy oil recovery process, Steam Alternating Solvent (SAS) process, is proposed and studied using numerical simulation. The process is intended to combine the advantages of the SAGD and VAPEX processes to minimize the energy input per unit oil recovered. The SAS process involves injecting steam and solvent alternately, and the basic well configurations are the same as those in the SAGD process.
Field scale simulations were conducted to assess the SAS process performance using typical Cold Lake reservoir conditions. These results suggested that in the field, the oil production rate of a SAS process could be higher than that of a SAGD process. The usually higher viscosity of the oil along the chamber boundary in the SAS process was largely compensated by higher relative oil phase permeability resulting from higher oil phase saturation. On the other hand, the lower oil viscosity in the SAGD process was balanced by lower oil phase relative permeability due to higher water saturation at the chamber front. Preliminary economic analysis indicated that comparing to the SAGD process, the SAS process might save 18% of the energy input for the same oil production.
