Two-Phase Equilibrium and Minimum Miscibility Pressure of CO2-DME-Oil Mixtures

  • Author / Creator
    Zhou, Ying
  • CO2 flooding is a widely used enhanced oil recovery (EOR) method (Jarrell et al., 2002). Dimethyl ether (DME) is potentially a good solvent and has good compatibility with both CO2 and hydrocarbons (Catchpole et al., 2009; Ratnakar et al., 2016a). Due to the good solubility of DME in both CO2 and oil, adding DME during CO2 flooding may lower the minimum miscibility pressure (MMP) and enhance the oil recovery efficiency. Therefore, it is necessary to study the phase behavior of CO2-DME-crude oil mixtures. Previous researchers used a constant binary interaction parameter (BIP) between CO2 and DME in Peng-Robinson equation of state (PR EOS) to model the phase equilibrium of CO2-DME mixtures. However, it is found that the BIP between CO2 and DME shows a dependence on temperature. Based on the fitting of two-phase equilibrium data for CO2 and DME mixtures, a linear temperature-dependent BIP correlation for CO2-DME system is firstly obtained. Since no previous researchers focus on the density prediction of CO2-DME system, three volume translation models are applied in PR EOS to improve the vapor-liquid density prediction for CO2-DME mixtures. The predicted results are compared with the experimental data in the literature. It is found that PR EOS with the volume translation model proposed by Abudour et al. (2013) provides the most accurate density prediction. In addition, it is essential to determine the minimum miscibility pressure (MMP) during CO2 flooding process. In the second part of the study, the multiple-mixing-cell (MMC) algorithm proposed by Ahmadi and Johns (2011) is adopted for MMP predictions. Prediction results show that adding DME during CO2 flooding can lower the MMP between injection gas and reservoir oil and thus help enhance the oil recovery efficiency.

  • Subjects / Keywords
  • Graduation date
    Spring 2021
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.