Temperature and Composition Effect on CO₂ Miscibility by Interfacial Tension Measurement

Abstract

Crude oil reservoirs have different temperatures, compositions, and pressures, therefore oil recovery performance by CO 2 injection varies from one case to another. Furthermore, it is predicted that lower interfacial tension between injected CO 2 and reservoir fluid results in more oil recovery. In this study, we investigate the effect of temperature on the equilibrium interfacial tension between CO 2 and three different oil fluids at different pressures. Also minimum miscible pressure (MMP) is measured by the vanishing interfacial tension (VIT) technique to determine the temperature effect on the CO 2 miscible gas injection. The results on different pure and mixtures of hydrocarbon fluids show that for pressures up to 5.2 MPa, the higher the temperature was, the lower was the interfacial tension (IFT) measured. However, for the cases with pressure higher than 5.2 MPa, as the temperature was increased, the IFT increased too. In addition the VIT technique is used to measure the MMP of CO 2 and pure paraffin; the heavier paraffin was, the higher was the MMP noticed. Also, we have learned that paraffin groups have an important effect on multicomponent interfacial tension behavior.

Influence of wettability and permeability heterogeneity on miscible CO2 flooding efficiency

“…Then the confining pressure was increased to 1800 psig and the backpressure was set at 1400 psig. The backpressure was chosen so that the CO 2 would be completely miscible with the oil phase (n-hexadecane) at the test temperature (24 ± 1°C) [30]. Absolute permeability of the core sample at the test, confining and backpressures was measured while flowing few more PVs of the brine.…”

Evaluation of interfacial mass transfer coefficient as a function of temperature and pressure in carbon dioxide/normal alkane systems

“…The equilibrium IFT of CO 2 /hexadecane mixture at P = 0.69-8.27 MPa and T = 273.15-393.15 K are shown in Fig. 4 [24]. It is obvious from the figure that equilibrium IFT reduces with increasing pressure due to higher solubility of gas at elevated pressures; however changes with temperature are not monotonic.…”

“…This equipment works based on axisymmetric drop shape analysis. Figure 1 shows the schematic of the experimental setup for IFT measurement between normal alkane and CO 2 samples [24,25].…”

“…The measurements of IFT were determined using the pendant drop method as described elsewhere [24,25]. To explain it briefly, prior to the experiment, the entire system (Capillary injector, Line connections, Bulk cylinder, Drop and View chamber) is cleaned with toluene and acetone followed by deionized water, finally dried by purging high grade nitrogen.…”

Interfacial resistance in CO2-normal alkane and N2-normal alkane systems: An experimental and modeling investigation

“…A high pressure cell with a volume of 20 cm 3 allows IFT measurements at different pressures and temperatures. The experimental setup has been described in details, elsewhere [31].…”