Determination of Minimum Miscibility Pressure Between Heavy Oil – Supercritical Carbon Dioxide System Using the Slim Tube Method

Abstract

Abstract The minimum miscibility pressure is the lowest pressure at which the reservoir fluid can be subjected in order to achieve miscibility with the desired gas. In this experimental study, a 40-ft slim tube, Haste alloy coil with an outer diameter of ¼″ was used to determine the minimum miscibility pressure (MMP) of a Heavy Oil-CO2 System at reservoir conditions. The slim tube was saturated with crude oil from a Niger Delta Field at a constant temperature of 139.2°F after which, 1.2 PV of supercritical carbon dioxide was injected above the heavy oil bubble point pressure at a constant flowrate of 0.2cc/min. The flooding process continued until a high-pressure drop was observed with minimal oil recovered. It was seen that the displacement efficiency increased with an increase in experimental pressures beyond a point where its increase was nominal. However, the MMP for this study occurred at a reservoir pressure of 2042 psi which is the break-over point where no significant change in oil recovery was observed with a recovery above 70%OOIP. The determined MMP was used as a guide in a CO2-EOR and CO2 secondary mode flooding project using a Niger Delta and tight Berea Buff reservoir core samples. The result shows that MMP plays a vital role in any successful miscible flooding EOR project. In the era of carbon capture and sequestration, we can therefore capture carbon and use it for EOR. However, the MMP of the crude oil has to be determined.