Interfacial Interactions between Reservoir Brine and CO₂at High Pressures and Elevated Temperatures

Abstract

In this paper, an experimental technique has been developed to study the interfacial interactions of the reservoir brine-CO 2 system at high pressures and elevated temperatures. Using the axisymmetric drop shape analysis (ADSA) for the pendant drop case, this new technique makes it possible to determine the interfacial tension (IFT) and visualize the interfacial interactions between the reservoir brine and CO 2 under practical reservoir conditions. More specifically, the dynamic IFT between the reservoir brine and CO 2 is measured as a function of pressure at two different temperatures. It is found that the dynamic IFT gradually reduces to a constant value, which is termed as the equilibrium IFT. The equilibrium IFT decreases as the pressure increases, whereas the same parameter increases as the temperature increases. The major interfacial interactions observed in this study include interface disappearance, the swelling effect, the shrinking effect, and wettability alteration. At an elevated temperature (T ) 58 °C), the pendant brine drop cannot be observed in the CO 2 phase at a pressure of P g 12.238 MPa. It is also found that CO 2 solubility in the brine phase, which is measured using the PVT system, approaches its maximum value under the same conditions. Further increases in pressure do not noticeably increase the CO 2 solubility in the brine phase. The brine swelling effect is observed at all the pressures and temperatures tested, whereas the brine shrinking effect occurs only at high pressures and a lower temperature (T ) 27 °C). In addition, the wettability of the reservoir brine-CO 2 system changes from the hydrophilic case to the hydrophobic case when the CO 2 changes from the gas phase to the liquid phase.

Study of the impact of high temperatures and pressures on the equilibrium densities and interfacial tension of the carbon dioxide/water system

“…At these conditions, pure CO 2 will be in a supercritical state (T c ~ 304.13 K and P c ~ 7.38 MPa) and with densities higher than 662 kg·m -3 . Due to its key role in the design of the processes mentioned above, many studies have been conducted on the experimental measurement of the IFT of the CO 2 /H 2 O system during the last two decades [6,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. In most of these studies the pendant drop method has been used to perform these measurements over a wide range of experimental conditions.…”

Experimental investigation of the CO2 sealing efficiency of caprocks

“…Chiquet et al (2007a) state that the maximum allowable CO 2 storage pressure may only exceed initial reservoir pressure by a fraction. Correlations of pressure and temperature with interfacial tension and wetting angle and their effect on CO 2 storage capacities have been investigated by Yang et al (2005), Chalbaud et al (2006Chalbaud et al ( , 2009 and Chiquet et al (2007a,b). In addition Shah et al (2008) demonstrated that the water-wettability of caprocks can vary in the presence non-wetting gas (CO 2 or H 2 S) and the mineral substance of the solid phase.…”

Analysis of Heavy Oil Emulsion-Carbon Dioxide System on Oil-Swelling Factor and Interfacial Tension by Using Pendant Drop Method for Enhanced Oil Recovery and Carbon Dioxide Storage

“…When the water content was higher, the dynamic IFT is almost constant from the very beginning. This means that the pendant drop and CO 2 can quickly reach the equilibrium state [10]. Fig.…”