Emulsion refers to a mixture that includes two or more liquid phases. The uses of emulsions are found in several chemical, energy, and environmental industries such as the food, health care, chemical synthesis, and firefighting sectors. Water‐in‐oil emulsions are formed spontaneously during oil production when oil and water are mixed together and in the presence of asphaltene as a naturally occurring surfactant. For operational and economic reasons, oil emulsions need to be treated to recover both oil and water phases. To develop more efficient emulsion treatments, it is essential to have a better understanding of the factors that affect emulsion formation and stability. The droplet size variation is an important parameter that influences the stability and rheological characteristics of the emulsions. In addition, the available interfacial area for any possible chemical reactions might affect the behaviours and properties of the emulsions in various transport phenomena systems. The adequate knowledge of the factors and mechanisms affecting the droplet size and emulsion stability still needs further engineering and research activities. This study is aimed to provide a comprehensive literature review on the formation of water/oil emulsions and their stability in various physical systems (e.g., pipeline networks and porous media). In this review, fundamental aspects of emulsions, emulsion formation mechanisms, analytical models, and numerical solutions for the description and characterization of the behaviours of emulsions in porous media and/or separators are discussed. The effects of different fluid properties, physical model characteristics, and operational conditions on emulsion behaviours are studied. This paper also summarizes the previous experimental and modelling studies and methodologies with a focus on reliable laboratory equipment/tools and simulation and modelling packages/strategies for the investigation of emulsion stability and droplet size distribution where a systematic parametric sensitivity analysis to study various effects of important thermodynamic, process, and medium properties on the targeted variables is conducted. This review manuscript provides useful guidelines to characterize and model emulsions and their behaviours in different industrial sectors, which will considerably help to conduct better design and optimal operation of corresponding equipment.

Multiphase systems and their behaviors/characteristics appear to be crucial in a variety of industries such as the oil and gas sector, pharmaceutical industry, and food industry. In this paper, the mesoscale simulation method is used to predict the interfacial behaviors of the water/oil systems at different temperatures and salt concentrations in the presence of a nonionic surfactant (hexaethylene glycol monododecyl ether). Dissipative particle dynamics (DPD) is employed to model the interfacial properties (e.g., interfacial density and interfacial tension) and structural properties such as the radius of gyration as a function of water/oil ratio, surfactant concentration, temperature, and salinity of oil/surfactant/water mixtures. Molecular dynamics (MD) simulations are carried out to estimate the Flory–Huggins chi parameter by means of temperature-dependent solubility parameter and cohesive energy calculations using Monte Carlo (MC) method, which is then utilized as an input for the DPD approach. The DPD repulsive interaction parameter (a ij ) is also obtained from the dependence of chi parameter to temperature using MD simulations. Both the density profiles and simulation snapshots indicate a well-defined interface between water and oil phases, where the thickness of the layer increases with increasing the surfactant concentration and the peak of density becomes higher accordingly. It is found that the radius of gyration is a weak function of salinity; however, it increases with an increase in the surfactant concentration, revealing that the surfactant molecules become more stretched at the interface. By increasing the water content or water/oil ratio (WC), the interfacial tension increases to reach a maximum value. After the maximum interfacial tension, increasing the water/oil ratio lowers this important parameter. According to the results of the MD simulations, the presence of salt improves the interfacial efficiency of the surfactant by decreasing the interfacial tension, which is in a good agreement with the literature data. Integrating the micro- and mesoscale modeling through chi parameter determination improves the accuracy of the calculations. This integration also decreases the calculation time (and costs). Employing the integrated modeling approach, the dynamic performance of the targeted systems can be thus well-reproduced with respect to the results reported in the literature. This research work offers useful tips for surfactant selection as well as important results and information on the interactions of molecules at water/oil interface, which are central to analyze emulsion stability at different process and thermodynamic conditions.

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Preventing hydrate formation is critical to safely and economically manage subsea tiebacks. Thermodynamic Hydrate Inhibitors (THI) and Low Dosage Hydrate Inhibitors (LDHI) help manage hydrate formation. Here, we use a novel isothermal approach using a PVT cell to experimentally find the hydrate equilibrium point of natural gas and brine. In addition, a constant temperature and pressure condition is used to compare hydrate formation with and without hydrate inhibitors. First, to better understand the novel isothermal technique, natural gas-brine equilibrium experiments were conducted. Secondly, a constant pressure and temperature approach is used to investigate Kinetic Hydrate Inhibitors (KHIs) and low dosage methanol performance on hydrate formation. The formation and dissociation points are detected through a sudden drop or peak in the pressure profile, respectively, and by visual observation. To evaluate inhibitor performance, the experiments were conducted at challenging temperatures between -0.5°C to 3°C, applicable to the environment offshore Newfoundland and Labrador. Two commercial KHIs and one THI were tested. Both KHIs showed good performance up to certain level of subcooling according to their concentration. However, KHI-B performed better at inhibiting hydrates compared to KHI-A despite its lower concentrations compared to KHI-A. The induction time for 1 wt% KHI-A under 10°C subcooling at a temperature of 0.75°C was 311 min. The induction time for 1 wt% KHI-B under 12°C subcooling at a temperature of 2.66°C was 184 min. Yet, in the case of KHI B, with half the concentration (0.5 wt%), no hydrate formed at temperature of 1.21°C and 10°C subcooling. Low dosage methanol (a common THI) was also assessed. Although the induction time under 10.36°C subcooling and constant temperature of −0.43°C was only 47 min, no hydrate formed within 22 hours at −0.12°C under 7.5°C subcooling. This work uses a novel experimental isothermal approach by PVT cell to investigate hydrate equilibrium and the effectiveness of different inhibitors. Hence, a better understanding of natural gas hydrate equilibrium in brine is developed. Based on significant costs associated with injecting high quantities of THI (e.g., methanol) to prevent hydrate formation, this work also compares the performance of KHIs and low dosage THI (methanol).