Determination of Minimum Miscibility Pressure in supercritical extractor using oil saturated sample

The main parameter for determination of the possibilities to enhance oil recovery by e.g. CO₂ injection into a specific oil field is the measurement of Minimum Miscibility Pressure (MMP). This pressure is the lowest pressure for which a gas can obtain miscibility through a multi contact process with a given oil reservoir at the reservoir temperature. The oil formation to which the process is applied must be operated at or above the MMP. Before field trial this parameter is to be determined at the laboratory which traditionally is done by help of a slim tube or a raising bubble experiments. However, in order to investigate the MMP, we suggest another method by using a supercritical extractor. Spe-ed SFE equipment with oil saturated natural rock samples were used for the purpose. The clean chalk samples were saturated with oil from the Dan field under vacuum. The CO₂ gas was injected into the extractor vessel containing the sample at different increasing pressure levels. The oil displaced in such a way was collected and measured. The volume of extracted oil was plotted against the increasing pressure. The form of the graph is similar to that typically obtained from a slim tube experiment. Following the breakover point criterion the MMP read from the plot was found equal to 20 MPa.