Techno-economic analysis of intermediate hydrocarbon injection on coupled CO 2 storage and enhanced oil recovery

This study proposes economic evaluation of CO 2 geological storage with enhanced oil recovery. The procedures consider capital expenditures and operating costs of infrastructures and revenues from oil recovery and carbon tax credits. Extensive CO 2 geological storage with enhanced oil recovery simulations was conducted to determine the most promising scenario among cases, where miscibility was controlled by the addition of liquefied petroleum gas. The addition of liquefied petroleum gas into a CO 2 injection stream can accelerate reduction of oil viscosity, interfacial tension, and oil density, which cause improved displacement efficiency. The larger was the amount of liquefied petroleum gas injected, the greater was the miscibility due to minimum miscibility pressure reduction, resulting in higher oil recovery and less CO 2 sequestration. Although liquefied petroleum gas addition enhances the performance of CO 2 enhanced oil recovery, economic analysis should be conducted for CO 2 geological storage with enhanced oil recovery due to the higher price of liquefied petroleum gas than that of CO 2 . Net present value decreased from liquefied petroleum gas mole fraction of 0–2% and started to increase from mole fraction 2–13% due to the miscibility effect. Then, net present value started to decrease, because the purchasing and injecting prices of the required liquefied petroleum gas exceeded that of the oil produced. Economic evaluation showed that addition of 13% liquefied petroleum gas was the most promising scenario, with a net present value of 91 MM$. Thus, we confirmed an optimum liquefied petroleum gas concentration in the CO 2 geological storage with enhanced oil recovery process.