Ethanol enhanced anionic surfactant solubility in CO2 and CO2 foam stability: MD simulation and experimental investigations. (1st May 2020)

• Record Type: Journal Article
• Authors: Zhang, Chao; Wu, Pingkeng; Li, Zhaomin; Liu, Tao; Zhao, Ling; Hu, Dongdong
• Is Part Of: Fuel. Volume 267(2020)
• Publication Date: 2020-05-01
• Subjects: CO2-soluble surfactant -- CO2 foam -- Foam stability -- Foam re-generalization -- Interfacial adsorption; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2020.117162
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: Ethanol enhances surfactant CO2 -soluble, foam stability and regeneration capacity. Molecular simulation to reveal effect of ethanol on CO2 -H2 O interfacial properties. Interfacial rheology and foam tension–compression test to analyze foam stability. Foam regeneration capacity in porous media is evaluated and analyzed. Abstract: CO2 foam has been widely scrutinized as a potential candidate in enhanced oil recovery while reducing CO2 emissions through geo-sequestration due to the high-efficiency CO2 mobility control ability. However, its application has been retarded partially because of the limited solubility of commercial and environmentally friendly surfactants in supercritical CO2 . In this work, the challenge of limited solubility of surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in CO2 is overcome by using ethanol as a co-solvent. The presented MD simulation reveals the underlying mechanism of the ethanol increased solubility of AOT in CO2 and the subsequently water-CO2 interfacial properties favorable for a stable CO2 foam. Experimental observation is in good accordance with the MD simulation that foamability and foam stability both significantly increase with ethanol as co-solvent, and their dependence on ethanol content. With ethanol as co-solvent to assist the dissolution of AOT in CO2, the CO2 foam has a high stiffness and the foam film has a high dilational modulus under high pressure of 15 MPa, which explain the stable CO2 foam. Experiments also show that ethanol helps the foam regeneration, making the practical oil field application of the presented system even more promising.