Kinetics of Crystallization of Aqueous Droplets in Water-in-Crude Oil Emulsions at Low Temperatures

Abstract

This study focused on the examination of the isothermal crystallization of aqueous droplets in water-in-crude oil emulsions with water concentrations in the range of 5 to 20 wt %. Experiments were carried out using differential scanning calorimetry (DSC) with temperatures ranging from −36 °C to −41 °C. The experimental results were approximated using a mathematical kinetic model including the effect of self-acceleration. The rate of crystallization increases with decreasing temperature, and the final accepted degree of crystallinity also increases along with a decrease in temperature. Correlation was observed between the kinetics of isothermal and nonisothermal crystallization. Furthermore, the complete crystallization in the isothermal process is reached at −40 °C; however, at high rates of cooling (10 to 20 °C/min), complete crystallinity is not achieved even at −50 °C. Complete crystallinity in the nonisothermal process can only be reached at cooling rates lower than 5 °C/min.

Rheology of Water-in-Crude Oil Emulsions: Influence of Concentration and Temperature

“…The drop size strongly affects the stability of the emulsion [33] against coalescence. In our previous works [34,35] the influence of droplet size and aqueous phase content on stability of water-in-crude oil emulsions (ϕ = 1-40%), which are the research objects of this work, has been studied by optical microscopy, NMR and Differential Scanning Calorimetry (DSC) techniques. It is found that the droplet size distribution and the mean droplet size can influence the emulsion stability.…”

Effect of Composition and Interfacial Tension on the Rheology and Morphology of Heavy Oil-In-Water Emulsions

“…The W/O emulsions appear spontaneously, for instance, during offshore petroleum production. Emulsions of this type with brine as a dispersed phase are widely highlighted in the literature. − The formation of W/O emulsions leads to high viscosity which makes the transportation of these unconventional oil resources challenging. − …”

Mutual Effects of Fe3O4/Chitosan Nanocomposite and Different Ions in Water for Stability of Water-in-Oil (w/o) Emulsions at Low–High Salinities

“…Various factors affect emulsion stability/instability. These factors include: Water/oil properties Droplet size of surface active agents: the surface area per unit of mass, as well as the surfactant adsorption on particles, increases as droplet size decreases Stirring rate and/or shear stress exerted; more energy should be exerted to form smaller droplets The percentage of oil and water in emulsion The type and amount of emulsifiers Free energy: spontaneous emulsification may occur if free energy value is negative Temperature: an increase in temperature facilitates emulsion breaking and results in instability of the surface film of the oil-in-water (o/w) emulsion, as a result of reduction in viscosity − …”

“…Temperature: an increase in temperature facilitates emulsion breaking and results in instability of the surface film of the oil-in-water (o/w) emulsion, as a result of reduction in viscosity − …”