Investigation of Gas Flow in SAGD
Canas, C., Kantzas, A. and Edmunds, N.
CIPC 2009-194, presented at the 60th Annual Technical Meeting of the Petroleum Society held in Calgary, June 16-18, 2009.
Non-condensable gases (CH 4, CO 2, and H 2S) are present and play an important role in the thermal efficiency of SAGD. However, the role of these gases is not well understood and it is regarded by some people as beneficial, yet detrimental by others. The characterization of the gas flow in SAGD is crucial to predict its effect on the process performance.
One mechanism involved in the flow of gas is the viscous drag due to the falling liquids in the SAGD chamber. In this work, the production of gas in SAGD was studied by deriving flow equations that describe the viscous drag in a gas-water-oil system. Two geometries have been studied; these are flow in a capillary tube and flow of a descending film on a plate.
The three-phase flow analysis has been extended to a macroscopic level in order to predict the amount of gas produced due to the viscous drag of the falling phases. The assumption that the reservoir behaves as a bundle of capillaries with a pore size distribution was made.
Results from this analytical model indicate that some of the gas in the steam chamber flows downwards and therefore could be produced by viscous drag of the falling liquids.