During steam assisted gravity drainage (SAGD) process, a steam chamber forms due to continuous steam injection. This chamber first moves upward to the top of the reservoir and then spreads sideways. The upward chamber displacement is one of the key factors for optimising the steam injection rate. It is necessary to determine the accurate chamber rise velocity for predicting the oil recovery rate. Recent experiments show that oil flow is coupled to water flow during three‐phase gravity drainage in water‐wet systems. In this paper, we argue that this type of flow coupling can be significant in SAGD operations. We extend Butler's [Butler, J. Can. Petrol. Technol. 1987, 26, 70] and Gotawala and Gates [Gotawala and Gates, Can. J. Chem. Eng. 2008, 86, 1011] analytic models for the rise of interfering steam chambers to account for three‐phase flow and flow coupling. We also show the importance of flow coupling by solving a simple numerical example. We observe that by including three‐phase drainage and the flow coupling at the steam finger edge, the vertical rise velocity of a steam chamber increases. Moreover, the rise velocity is very sensitive to the coupling term introduced in the new models. Even a small value of the coupling term increases the rise velocity significantly. Furthermore, we compare the model predictions with the values measured in six fields.

The existing models for steam chamber rise rate ignore the effect of water drainage that can result in three-phase flow near the finger/chamber edge. We hypothesize that a steam finger can be divided into three different regions with different pore scale displacement mechanisms. We develop the flux equations for the three regions by assuming 1) negligible oil flow inside the finger, 2) three-phase flow in the transition zone, and 3) single-phase oil flow beyond the transition zone. We further assume that oil flow is coupled to water flow in the transition zone where the dominanat pore-scale mechanisms are double displacement, coalescence, and film drainage. The model results suggest that fast drainage of water in the transition region enhances the oil displacement rate due to the flow coupling. However, increase of the transition zone thickness, due to slow water drainage, decreases the chamber rise rate because of the decrease in the rate of heat conduction to the cold bitumen.