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.
Athabasca reservoir oil and sand were used to obtain the experimental data using the unsteady state method for relative permeability measurements. First the SAGD residual oil saturations were measured at 180, 200, and 220 °C. Then the oil displacement data collected during hot water and steam injection experiments were utilized to construct the relative permeability curves at different 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 objective of this study is to develop a series of realistic relative permeability curves that are representative of various downhole operating conditions that are encountered in Western Canadian oil-sand operations. The experimental results indicate that oil residual saturation decreases as temperature is increased. A noticeable change in oil residual saturation was also observed when phase change occurred from liquid water to steam phase at a given temperature. Finally, 3 sets of relative permeability curves were developed covering a wide range of SAGD operating conditions.