Gas (air)–heavy oil displacement in capillary media at high temperatures: A CFD approach to model microfluidics experiments

• Residual oil saturation during heavy oil displacement by gas was investigated.
• Residual oil diminished at higher temperature at the same gas rate.
• The decrement of residual oil with respect to time obeys an exponential function.
• As contact angle increased, residual oil diminished lineally for all temperatures.
• All oil was completely swept for contact angles above of 60° at 85 and 200°C

Displacement of heavy-oil by gas at elevated temperatures and residual oil saturation (Sor) development on the walls of a square capillary were investigated through computational fluid dynamics (CFD). The displacements were carried out at 55 and 85 °C and compared to experimental data showing good quantitative and qualitatively agreement. On the basis of these results, the behavior of Sor was explored at 200 °C, a typical temperature of thermal oil recovery (steam injection) applications. It is shown that Sor decreases at higher temperatures for a fixed air injection velocity. This numerical study suggests that the Sor diminishes exponentially with time until it reaches a constant value along the square capillary during the displacements. It also indicates that when the contact angle is increased, the retention of oil decreases lineally. Above 60°, oil is completely swept at 85 °C and 200 °C.This is the first attempt with CFD to analyze the retention of oil in the pores of a reservoir after the application of thermal methods. CFD approach to model this microscopic phenomenon is promising to carry out further research at temperature and pressure conditions that are very difficult to generate at the microscopic scale in laboratory experiments.