EXPERIMENTAL DETERMINATION OF MINIMUM MISCIBILITY PRESSURE BY GAS OIL IFT MEASUREMENTS FOR A GAS INJECTION EOR PROJECT

Knowledge of minimum miscibility pressure (MMP) plays a key role in the success of any miscible gas injection EOR project. Various theoretical methods but few experimental methods are available for confidently determining the MMP at reservoir conditions using actual reservoir fluids. The present experimental study reports on the determination of minimum miscibility pressure (MMP) for recombined live oil with CO2 at reservoir temperature using the vanishing interfacial tension (VIT) technique. It relies on the measurements of gas‑oil interfacial tension at several pressures and reservoir temperature. MMP is then obtained by extrapolation of the measured data to zero interfacial tension. In the present study, interfacial tension (IFT) between two recombined live oil samples and CO2 was measured at reservoir temperature of 289C_B0F and at several pressures above the bubble point pressure of 2593 psia using the pendant drop method and the capillary rise technique. The pressure was then increased in steps to approach a near zero gas‑oil IFT condition. The MMP that corresponds to the pressure of zero IFT was obtained by extrapolating the measured values of gas‑oil IFT to zero on an IFT vs. Pressure plot. Such extrapolation yielded MMPs of 3533 psia and 3543 psia for the two recombined live oil samples. This study was conducted to aid in the implementation of a proposed miscible CO2 flood in a newly discovered oil field in Mississippi by comparing the results of an independently conducted Equation of State (EOS) modeling study based on vanishing tie‑line method. Measured VIT‑MMP was slightly lower compared to the EOS‑estimated MMP (3685 psia). This experimental study reinforces the use of VIT technique as robust experimental method for determining the MMP and to use this to validate EOS models before using them in compositional simulation studies.