Determination of the minimum miscibility pressure of the CO2/oil system based on quantification of the oil droplet volume reduction behavior

CO2 miscible flooding is one of the most ideal scenarios in oil recovery practices. Accurate prediction of the minimum miscible pressure (MMP) of the CO2/oil system is essential for CO2 Enhanced Oil Recovery (CO2-EOR) and carbon geological storage applications. In this paper, a novel method based on quantification of the oil droplet volume shrinkage behavior is proposed and demonstrated in the determination of the MMP of the CO2/nhexadecane (n-C16H34) system and the CO2/n-octadecane (n-C18H38) system. Based on the specific quantitative criterion of the oil droplet volume reduction rate, the MMPs of the CO2/oil system under different temperature levels were determined. The accuracy of the measurement results has been validated with the corresponding thermodynamic phase equilibrium calculation results. To show the application potential of the proposed method, detailed discussions have been provided based on comparisons with the Vanishing Interfacial Tension (VIT) method. It is expected the proposed Oil Droplet Volume Measurement (ODVM) method could act as a robust supplementary for studying the miscibility characteristics of the CO2/oil system.