MD simulations of oil-in-water/water-in-oil emulsions during surfactant-steam co-injection in bitumen recovery

Emulsion formation during bitumen production has been observed since the early stages of its production, resulting in obstacles that need special treatments. Understanding the types of emulsions and interactions between water and bitumen inside the emulsions is essential to address such issues. Hence, this paper considers different emulsion types, including water-in-oil and oil-in-water, to comprehensively evaluate an emulsification process in a surfactant-assisted thermal bitumen recovery method. Furthermore, different molecular analyses, including hydrogen bonds, a radial distribution function (RDF), hydration residence time, and interaction energy, were implemented to evaluate the mechanisms behind emulsification scenes during a surfactant-steam co-injection (SSCI) process. According to the results, a surfactant can improve the interaction between the water/steam phase and bitumen in water-in-oil and oil-in-water emulsions, resulting in higher interaction energy. Moreover, a hydrogen-bonding network between bitumen polar fractions and the aqueous phase was improved by adding the surfactant. This work lays the fundamentals about the emulsification process in a surfactant-steam co-injection process, essential for surfactant formulation in such in-situ thermal-based processes. Outcomes of this work provide vital information about the emulsification of surfactants during the SSCI process and improve the efficiency of the design of such processes.