Abstract
Steam-assisted gravity drainage (SAGD) is a promising approach for recovering heavy and viscous oil. The success of SAGD relies on two key operations: uniform formation of the steam chamber along the full length of the injector, and effective control of steam breakthrough by sustaining a liquid level between the injector and producer (i.e. a steam trap). Intrinsic permeability heterogeneities typically lead to a partially-developed steam chamber and potentially low sweep efficiency that results in reduced oil production. The injectivity variability along the well also complicates the control of steam breakthrough. To overcome these difficulties, we propose the use of foamed steam. The feasibility of foam-assisted SAGD (FA-SAGD) is demonstrated numerically with a local-equilibrium foam simulator incorporating the physical mechanisms of foam generation, destruction, and transport. The model was validated previously. Simulation results show that strong foam is generated and accumulates in the interwell region. The presence of foamed steam helps to control steam breakthrough and yields better recovery performance per barrel of steam injected than conventional SAGD. Live steam production in simulations is reduced by a factor of 5. Consequently, cumulative oil production is increased by about 30% in comparison to cases without foam. Sensitivity analysis of the parameters describing foam indicate that the process is robust.
