Simulation of Noncondensable Gases in SAGD-Steam Chambers

Abstract

Summary Cenovus Energy has been developing the Foster Creek and Christina Lake projects using the steam-assisted gravity-drainage (SAGD) process successfully. The SAGD process at both these projects has been operated at well above the initial reservoir pressure for extended periods of time and this has been simulated adequately using dead-oil models, which omit solution gas from the simulations. As we move into later stages in the life of the more mature well pairs at these projects, it is important to understand the role of noncondensable gases on the development of the steam chambers better in order to optimize the methane-coinjection, steam rampdown, and, ultimately, blowdown phases of operations. Cenovus is also testing reduced-pressure SAGD and solvent-aided processes (SAPs) at these projects, and simulations indicate that noncondensable gas will play a significant role in these processes. Hence, understanding the flow behaviour of noncondensable gases in SAGD steam chambers could have far reaching consequences for lowering the energy intensity and associated costs, and reducing the environmental impact of bitumen production while potentially increasing reserves. This paper presents the results of some recent simulations which are improving our understanding of the role of solution gas in SAGD and the impact of noncondensable gases on steam chamber development.