Modeling and simulation of the penetration of a compound droplet into a throat in a pore-throat structure

Crude oil in underground porous media can be emulsified by surfactants, which can lead to improved oil recovery. However, there have been limited investigations revealing the interactions between emulsions and grains and comparing the influence of different factors on the distribution of emulsions in porous media at the pore scale. In this study, a solution containing surfactant was injected into an oil-saturated microchip with heterogeneous pore geometries. A series of tests were conducted by varying the injection rate, surfactant concentration, oil viscosity, and displacing phase viscosity. Qualitative analysis of flow mechanisms and quantitative analysis of the distribution of emulsions were performed through pore-scale snapshots. The results demonstrate that emulsions undergo deformation, breakup, and retention in porous media. Furthermore, new micro-interactions between emulsion droplets and grains are discovered, including the impact effect, cutting effect, and the synergy of both effects. A high flow rate of the displacing phase promotes the formation of more and smaller emulsions, while a low flow rate encourages flow diversion. An increase in oil viscosity and a decrease in surfactant concentration are not conducive to the formation of emulsions. However, an increase in the displacing phase viscosity promotes the formation of emulsions and flow diversion. The experiments provide detailed insights into the flow behaviors of emulsions at pore scale and offer valuable information for surfactant flooding.

Investigation of microflow mechanisms and emulsion size distribution in porous media

Wang,

Wei,

Hou

et al. 2023

Numerical study of compound drop mobility over a surface having wettability difference

Pathak,

Singh,

Das

2023

Three-dimensional numerical simulations have been performed to analyze the effect of wettability difference on a compound droplet through biphilic and wettability gradient surfaces. Three distinct drop–drop configuration regimes during translation are found in both types of surfaces, as the contact angle difference on the surface is varied. Along with these advancing, rear, and central locations of core drop regimes, lens like drop–drop configuration is also realized over the biphilic surface by considering hydrophobic contact angle variation. On the biphilic surface, drop–drop configurations are also reported from simulation with different core-to-shell volume ratios and inversion of core and shell liquids.

A numerical investigation on the morphology evolution of compound droplets

Lv,

Ji,

Zhang

et al. 2024

The volume of fluid-continuum surface force model is used to systematically study the influence of characteristic parameters, internal pressure on the dynamic characteristics, finite deformation mode, and fracture mode of compound droplets in air. The simulation results indicate that the morphology evolution of compound droplets can be divided into two stages: expansion deformation stage and irregular deformation stage. And for the first time, it is proposed that the crushing methods of compound droplets can be divided into two types: overall oscillation and local oscillation. Increasing the internal pressure of the compound droplet will cause severe deformation of the compound droplet, and the time required for the expansion and deformation stage will be reduced. However, the influence of fluid interfacial tension and viscosity on the bottom dynamics of compound droplets is often complex, leading to significant changes in the deformation mode of compound droplets. In addition, the influence of feature parameters We and Ca is further discussed. The research results can provide theoretical guidance for precise control of their arrangement in core–shell driven microfluidic technology.