Propane–Bitumen Interactions during Cyclic Solvent Injection─A Cold Lake Case Study

Abstract

Common bitumen recovery processes, such as steam-assisted gravity drainage (SAGD) and vapor extraction (VAPEX), are not suitable for thin reservoirs due to the heavy consumption of water and heat and the lack of a gravity drainage mechanism. As an alternative, cyclic solvent injection (CSI) at low temperatures has been developed as a more sustainable and energyefficient technique for bitumen recovery from oil-sand reservoirs. This study aims to conduct specific CSI experiments to address the following questions: (1) How does the propane phase affect bitumen recovery? (2) What mechanisms control bitumen recovery at different propane phases? We synthesized core plugs from in situ oil-sand and bitumen samples of the Clearwater Formation at Cold Lake. Three CSI experiments were conducted by liquid propane (C 3,L ), two-phase propane (C 3,V−L ), and vapor propane (C 3,V ) in a state-of-the-art visualization cell equipped with a camera and a digital pressure transducer. We calculated the bitumen recovery factor (RF b ) by the weight-balance method and analyzed the pressure profiles and images from the core face during the three experiments. The results show that RF b by C 3,V is higher than that by C 3,L . In addition, we observed that when CSI is conducted by C 3,L , the core face is plugged by asphaltene deposition. Furthermore, in CSI by C 3,L , limited bitumen recovery occurs when pressure is dropped below the saturation pressure of propane during depletion. The results also suggest that the combination of asphaltene deposition, solution gas drive, oil extraction, and production under wormhole support are the mechanisms controlling bitumen recovery from oil-sand cores.