Experiment and correlations for CO2–oil minimum miscibility pressure in pure and impure CO2 streams

Abstract

Miscible gas flooding is one of the most effective methods for enhanced oil recovery (EOR). A key and important parameter in designing an efficient miscible gas flooding is the minimum miscibility pressure (MMP). It is very essential to determine and predict gas–oil MMP for EOR technology. In this work, both the experiment and correlation approaches for obtaining gas–oil MMP were studied. Experimentally, a set of apparatus with the vanishing interfacial tension (VIT) technique was set up and utilized to determine the gas–oil MMP for three different kinds of injection gas. Theoretically, a new model was proposed to predict the gas–oil MMP. A total of 156 experimental MMP data were achieved from this work and literature was used to train and test the model. The average absolute relative deviations (AARD%) of the training set for pure CO₂, CO₂ mole fraction less than 0.5 (x_CO2 < 0.5) and CO₂ mole fraction larger than 0.5 (x_CO2 > 0.5) in the injection gas are 5.85%, 4.06% and 6.49%, respectively. The AARD% of the testing set are 2.08%, 2.97% and 5.26%, respectively. The model is applied to calculate the gas–oil MMP in different CO₂ purity flooding with CO₂ mole fraction in the injection gas from 0.0352 to 1.