Experimental Investigation of Asphaltene Content Effect on Crude Oil/CO2 Minimum Miscibility Pressure

Abstract

Minimum Miscibility Pressure (MMP) is regarded as one of the foremost parameters required to be measured in a CO2 injection process. Therefore, a reasonable approximation of the MMP can be useful for better development of injection conditions as well as planning surface facilities. In this study, the impact of asphaltene content ranging from 3.84 % to 16 % on CO2/heavy oil MMP is evaluated. In this respect, slim tube miscibility and Vanishing Interfacial Tension (VIT) tests are used. Regarding the VIT test, the Interfacial Tension (IFT) is measured by means of two methods including pendant drop and capillary apparatuses, and thereafter the MMP measurement error between slim tube and VIT methods are calculated. Based on the results, by increasing the asphaltene content, the measured MMP by slim tube method increases linearly while that by VIT follows no clear trend. The results also indicate that there is an asphaltene content range within which the MMP error between slim tube and VIT tests is minimized. IFT measurement by pendant drop and Capillary Glass Tube (CGT) methods show that by increasing asphaltene content up to 10.15 %, IFT declines, whereas for further increase in content, IFT increases because of the irregular dispersion of asphaltene in oil droplets.

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“…However, at higher concentrations, asphaltenes can aggregate and form larger structures. These larger structures may not be as effective at reducing IFT. , Moreover, high-density and high-viscosity fluids typically have higher IFT because they have greater molecular complexity and are less mobile, making it more difficult for them to spread and mix with other fluids at the interface. , …”

“…These larger structures may not be as effective at reducing IFT. 85,86 Moreover, high-density and high-viscosity fluids typically have higher IFT because they have greater molecular complexity and are less mobile, making it more difficult for them to spread and mix with other fluids at the interface. 83,87 As can be seen, by increasing the salinity from DIW to 1.5 SW, the IFT consistently decreased.…”