The Role of Shearing Energy and Interfacial Gibbs Free Energy in the Emulsification Mechanism of Waxy Crude Oil

Abstract

Abstract:Crude oil is generally produced with water, and the water cut produced by oil wells is increasingly common over their lifetime, so it is inevitable to create emulsions during oil production. However, the formation of emulsions presents a costly problem in surface process particularly, both in terms of transportation energy consumption and separation efficiency. To deal with the production and operational problems which are related to crude oil emulsions, especially to ensure the separation and transportation of crude oil-water systems, it is necessary to better understand the emulsification mechanism of crude oil under different conditions from the aspects of bulk and interfacial properties. The concept of shearing energy was introduced in this study to reveal the driving force for emulsification. The relationship between shearing stress in the flow field and interfacial tension (IFT) was established, and the correlation between shearing energy and interfacial Gibbs free energy was developed. The potential of the developed correlation model was validated using the experimental and field data on emulsification behavior. It was also shown how droplet deformation could be predicted from a random deformation degree and orientation angle. The results indicated that shearing energy as the energy produced by shearing stress working in the flow field is the driving force activating the emulsification behavior. The deformation degree and orientation angle of dispersed phase droplet are associated with the interfacial properties, rheological properties and the experienced turbulence degree. The correlation between shearing stress and IFT can be quantified if droplet deformation degree vs. droplet orientation angle data is available. When the water cut is close to the inversion point of waxy crude oil emulsion, the interfacial Gibbs free energy change decreased and the shearing energy increased. This feature is also presented in the special regions where the suddenly changed flow field can be formed. Hence, the shearing energy is an effective form that can show the contribution of kinetic energy for the oil-water mixtures to interfacial Gibbs free energy in emulsification process, and the emulsification mechanism of waxy crude oil-water emulsions was further explained from the theoretical level.

Spontaneous Emulsification via Once Bottom-Up Cycle for the Crude Oil in Low-Permeability Reservoirs

“…Accordingly, there is the lowest IFT value at different compound ratios. Correspondingly, all of the compound systems can generate the SE with the lower Gibbs interface free energy. , Eventually, the optimum formulation of the SE system is decided to be 0.4% (7:3 APG1214/HABS) + 0.1% NaOH.…”

Synergistic Effects of Aqueous Phase Viscoelasticity and Reduced Interfacial Tension on Nonwetting Phase Displacement Efficiency: An In Situ Experimental Investigation

“…To break a large oil globule into small droplets, the displacing phase (the VES solution in this case) needed to exert a certain amount of energy on that globule. The minimum required work is equal to the variation of the surface Gibbs free energy of the oil blob during the fragmentation process and can be calculated using the following equation normalΔ G = σ normalΔ A where Δ G is the change in the surface Gibbs free energy of the oil blob in mJ, Δ A is the change in oil blob surface area in m 2 during the breakup process, and σ is the oil/brine interfacial tension in mN/m.…”

Molecular Dynamics-Based Simulation on Chemical Flooding Produced Emulsion Formation and Stabilization: A Critical Review

“…Therefore, to realize stable emulsions, one should slow down or fully hinder droplet coalescence through the addition of emulsifiers, that is, increase the kinetic stability of emulsions [13]. Emulsions are ubiquitous in crude oil production and can be broadly classified into water-in-oil (W/O), oil-in-water (O/W), and multilevel or complex emulsions [14].…”