Enhancing Sodium Bis(2-ethylhexyl) Sulfosuccinate Injectivity for CO2 Foam Formation in Low-Permeability Cores: Dissolving in CO2 with Ethanol

Abstract

The utilization of conventional water-soluble surfactants for the stabilization of CO2 foams has been limited by the low injectability of low-permeability reservoirs. In this study, the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used as the CO2-soluble surfactant to stabilize CO2 foams in the presence of ethanol. The phase equilibrium relationships of the AOT/ethanol/CO2 system and the partition coefficient of AOT between supercritical CO2 (SC-CO2) and water were measured through a fully visible pressure–volume–temperature (PVT) cell. In addition, the effects of the ethanol content on the partition coefficient and interfacial tension (IFT) were studied. Furthermore, a laboratory apparatus was developed to measure the viscosity and injection performance of AOT dissolved in an aqueous or SC-CO2 solution and SC-CO2 foams. The experimental data show that addition of ethanol can significantly improve the solubility of AOT in SC-CO2 and increase the partition coefficient of AOT. The IF...