Application of the Marangoni Effect in Nanoemulsion on Improving Waterflooding Technology for Heavy-Oil Reservoirs

Abstract

Summary Waterflooding is considered an important cold-production method because it is economically advantageous for heavy-oil-reservoir development; however, its efficiency is not remarkable because of the adverse oil/water-mobility ratio and cold damage from solid-state adsorption. To address this problem, oil/water emulsion is critical for improving the recovery by significantly altering oil mobility. Previous research is mainly focused on the effect of surfactants, salinity, and water/oil ratio on emulsion formation, rather than on the effect of kinetic energy under low or no shear stress on emulsification. In this study, experiments are conducted using a microscope to observe oil/water interfacial turbulence (Marangoni effect) when oil is dropped into a nanoemulsion. The purpose of this study is to form an emulsion using the interfacial turbulence under low or no shear stress, to improve heavy-oil recovery under waterflooding. The interfacial movement between a nanoemulsion and oil and the mechanism of formation of the emulsion are investigated. The Marangoni effect and mass transfer are observed by use of a microscope and low field nuclear magnetic resonance (NMR), respectively. Nanoemulsion, along with other methods of chemical enhanced oil recovery (EOR), is compared by conducting coreflooding and sandpack-flooding experiments after waterflooding. The results show that the Marangoni effect can help to emulsify and remove the oil from oil sand by converting interfacial energy into kinetic energy. On the basis of flooding-experiment results, we conclude that slug injection with a combination of nanoemulsion flooding and polymer flooding is an effective method for improving heavy-oil recovery.