Relative permeability plays a significant role in predicting oil rate and estimating the ultimate oil recovery factor. Although it is known that the relative permeability can change with temperature, the same set of relative permeability is often used to predict the reservoir performance regardless of the temperature range involved in the process. This can lead to significant errors when the relative permeability changes appreciably with temperature.
A typical Athabasca oil and reservoir sand were used to obtain the experimental data using the unsteady state method. First the SAGD residual oil saturations in presence of hot water and steam were measured at 180, 200, and 220 ºC. Then oil displacement data collected during hot water and steam injection experiments were utilized to construct the relative permeability curves at given operating temperatures. Finally, a series of reservoir simulations were performed to history match the lab experiments and examine the accuracy of inferred relative permeability curves.
The experimental results indicate that oil residual saturation decreased as temperature increased. A noticeable change in residual saturation was also observed when phase change occurred from liquid to steam phase at a given temperature. Two correlations have been developed for predicting residual oil saturation as function of temperature for hot water and steam floods. Finally, three sets of relative permeability were developed covering a wide range of SAGD operating conditions.