A comprehensive visual study on in-situ oil-in-water and water-in-oil emulsification through oil thin film in oil-wet and mixed-wet porous media: A microfluidic approach

Abstract

In-situ emulsification is a promising process for reducing residual oil saturation in depleted reservoirs by transporting the oleic phase through oil-in-water (O/W) emulsions and blocking high permeable zones in invaded areas. In this study, various in-situ emulsification mechanisms are demonstrated visually based on the snap-off mechanism by choosing suitable low saline water (LSW), alkali, and surfactant (A.S) based on the type of crude oil. Results show that water-in-oil (W/O) emulsification in the oil thin film at swept zones creates a suitable condition for improving viscosity, swelling the oleic phase, and pushing residual oil from dead-end pores. Moreover, O/W emulsification in swept zones from ruptured oleic thin films can block high permeable pores and change the direction of the flow path towards low permeable pores. In addition, this study introduces several novel in-situ emulsification mechanisms and a novel procedure for measuring the in-situ interfacial tension (IFT) in porous media. Finally, the effects of injection rate on the emulsification, diversity of emulsion size, aggregation mechanism, differential pressure, and oil recovery factor are investigated. Overall, the study provides important insights into the mechanisms of in-situ emulsification in porous media and highlights its potential for enhancing oil recovery (EOR).