“…Research using hydrocarbon gas or CO 2 as a solvent has been conducted, from the laboratory to the field, for decades [3,5,6]. Additionally, research is being conducted to improve oil recovery and economic efficiency using a mixed solvent of CO 2 and hydrocarbon gas or a surfactant [7][8][9][10]. In particular, according to previous studies that added liquefied petroleum gas (LPG) to CO 2 flooding, LPG increases the displacement efficiency by reducing the minimum miscible pressure (MMP), which accelerates the effects of oil viscosity reduction, interfacial tension (IFT) reduction, and oil swelling, resulting in an increase in oil recovery [6,11,12].…”