Minimum Miscibility Pressure Using the Multiple Mixing-cell Combined with the PC-SAFT Equation of State

The minimum miscibility pressure (MMP) is one of the crucial and substantial parameters in the gas injection projects for enhanced oil recovery (EOR). This parameter indicates the minimum pressure at constant temperature and composition conditions for reaching 100 percent of the oil production recovery, which leads to a huge economic income. Therefore, an inaccurate prediction of the MMP may lead to increase the costs of oil production. Among the various methods for prediction of the MMP: slim-tube experiment, slim-tube simulation techniques and their simplified cell-to-cell could be considered as the most accurate methods. Although the experimental methods for calculation of the MMP take into account the real crude oil, but they are always expensive; therefore, thermodynamic simulation is a better way for the estimation of this parameter. Indeed, the analytical methods are fast and some of them like multiple mixing-cell method used in this study lead to the reliable results and often show good agreements with the experimental methods. A combination of multiple mixing-cell model proposed by Ahmadi-Johns and pressure-temperature (P-T) flash calculations including the PC-SAFT equation of state (EoS), and the cubic equations of state of Peng-Robinson (PR) and Esmaeilzadeh-Roshanfekr (ER) were used in this work for the prediction of MMP. The overall AAD% of the PC-SAFT, PR and ER EoSs were 3.49%, 6.32% and 7.59%, respectively. It is concluded that the SAFT EoS can decrease the AAD of MMP calculation by about 50%.