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

摘要

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.