A Mechanism of Gas Production in SAGD
Canas, C. and Kantzas, A.
SPE 157773, presented at the SPE Heavy Oil Conference Canada, held in Calgary, Alberta, June 12-14, 2012.
The dissolution of gas in both water and bitumen as a mechanism contributing to gas production in SAGD is studied. The contribution of this mechanism to the production of gas in SAGD is evaluated through the implementation of appropriate thermodynamic models into a series of numerical simulations in order to more accurately represent the physics of gas behavior inside the SAGD chamber. Methane, carbon dioxide and hydrogen sulphide are considered.
It is observed from the numerical simulation results that the production of a gas in SAGD is directly proportional to the solubility of that gas in the liquid phases being produced. Additionally, these results lead to the conclusion that gas dissolution is an important mechanism in gas production.
Results from this study also confirm the findings observed by other researchers that gas will accumulate at the front and top of the SAGD chamber, thus reducing SOR and oil production rates. The degree of such accumulation of gas depends, among other operational and reservoir conditions, on the solubility of that gas in the liquid phases under the temperature and pressure conditions inside the steam chamber.