Measurements and Modeling of Interfacial Tension for CO2/CH4/Brine Systems under Reservoir Conditions

Abstract

Supercritical CO2 injection is a promising way to hydraulically fracture tight/shale gas formations as well as enhance gas recovery from these formations. Understanding of phase behavior and interfacial tension (IFT) of CO2/CH4/brine (NaCl) systems is important, because they affect the performance of such a process in tight/shale gas formations. In this study, we employ the axisymmetric drop shape analysis (ADSA) method to measure the IFT between CO2/CH4 mixtures and brine over the temperature range from 77.0 to 257.0 °F and the pressure range from 15 to 5027 psia. Test results show that the presence of CO2 decreases the IFT of CH4/H2O or CH4/brine (NaCl) systems, while the degree of reduction depends on the molar fraction of CO2 in the gas mixture. Salinity tends to cause an increase in IFT of CO2/CH4/brine (NaCl) systems; a higher salinity leads to an increased IFT for a given system. On the basis of the Parachor model (Weinaug and Katz J. Ind. Eng. Chem. 1943, 35, 239) and Firoozabadi’s model (Firoozab...