Effects of the surfactant, polymer, and crude oil properties on the formation and stabilization of oil-based foam liquid films: Insights from the microscale

Abstract

Stable foams frequently hinder the efficient treatment of liquids produced by chemical flooding. Studies into the formation and stabilization mechanisms of these foams, are therefore essential to overcoming this problem in oilfield surface systems. However, previous investigations have mainly focused on water-based foams. Although a small number of studies have examined oil-based foams, only a few well-known properties similar to those of water-based foams have been reported. Therefore, in this study, different oil-based foam systems were prepared to investigate the impact of the surfactant (sodium dodecyl benzene sulfonate, SDBS), the polymer (partially hydrolyzed polyacrylamide, HPAM), and physical properties of the crude oil, on the foaming characteristics and the foam liquid film drainage behavior of liquids produced by chemical flooding. For this purpose, molecular dynamics (MD) simulation were employed, and the simulation results were verified experimentally. It was found that the SDBS molecules aggregated to form micelles on the liquid film of the oil-based foam; this contrasts to the directional adsorption observed at the gas − liquid interfaces of water-based foams. In addition, upon increasing the SDBS adsorption concentration at the gas − liquid interface, the formation ability and stability of the liquid film of the oil-based foam system were enhanced. Furthermore, an increase in the HPAM concentration increased the coverage area of the co-adsorption layer of the liquid film, thereby strengthening the stability of the foam system. However, upon increasing the HPAM concentration from 150 to 450 mg/L, the absolute value of the interfacial formation energy decreased from 511.16 to 495.70. This indicates that the liquid film formation ability of the foam system decreased with an increasing HPAM concentration. This was attributed to the fact that an increase in the carbon number of the straight-chain alkanes present in the foam system decreased the liquid film drainage rate and the possibility of Ostwald ripening. These new insights provide support for the design and development of new defoaming processes.