文摘
In this paper, cyclic solvent injection (CSI) and waterflooding (WF) were combined and studied to maximize their technical synergy and optimize the enhanced heavy oil recovery (EHOR) in the post-cold heavy oil production with sand (CHOPS) reservoirs. The original heavy oil sample was collected from the Colony formation in western Canada. The PVT data and viscosities of CH4/CO2/C3H8-saturated heavy oil were measured at different equilibrium pressures and Tres = 21 °C. A total of eight sandpacked laboratory tests were conducted to study and compare four different EHOR processes after the primary production: CSI, CSI + WF, simultaneous CSI + WF, and WF + CSI. In the last three processes, WF was applied after, simultaneously with, and prior to the CSI production, respectively. Three different pressure drawdown rates (6.8, 12.5, and 25.0 kPa/min) and two different solvents (CO2 and C3H8) were used to determine their specific effects on CSI + WF. The experimental results showed that CSI + WF had the highest heavy oil recovery factor (RF) of 30.1% in comparison with 28.9, 25.9, and 24.3% for WF + CSI, simultaneous CSI + WF, and CSI, respectively, when CO2 was used in CSI. The intermediate pressure drawdown rate of 12.5 kPa/min resulted in the highest heavy oil RF in CO2-CSI + WF. In addition, C3H8 was found to be a more effective extracting solvent than CO2 due to its more favorable PVT properties and larger heavy oil viscosity reduction.