Swelling Performance of Paraffinic Crude Oil Under Carbon Dioxide Injection

Paraffinic crude reservoir is one of an attractive options for co-implementation of CO2-EOR and CO2-storage activities. The effectiveness of oil recovery is affected by an oil swelling mechanism. The swelling performance of CO2 in paraffinic crude is essential to be studied due to the difficulties to pursue miscible condition. This mechanism was investigated through the analysis of the swelling factor value from the swelling experiment. Moreover, the equation of state calculation (EOS) using Peng–Robinson equation was performed to predict the minimum miscibility pressure (MMP) of the crude sample for investigating swelling trends toward this point. Results from the experimental test reveal a slow process of oil swelling due to CO2 injection, which is implied from the low swelling factor value. The EOS calculation shows a large MMP value, which was impossible to reach under reservoir condition. Extrapolating extraction-condensation trend indicates no occurring extraction which means that the main mechanisms for this crude type was dominated by viscosity and interfacial tension reduction. Although it was impossible to pursue the MMP, the utilization of CO2 in paraffinic crude may bring a positive impact on the oil recovery process.