Spotlight onto Surfactant-Steam-Heavy Oil System Behavior: Molecular Dynamic Study

Mohammadali Ahmadi


This work shows that the asphaltene architecture, resin and surfactant structures significantly affect surfactant-asphaltene interactions. A benzene ring in the surfactant structure can improve the interaction between surfactant and asphaltenes. Having sulfur heteroatoms in the resin structure can increase an interaction between SDBS and asphaltenes for both archipelago and island architectures. However, resin with sulfur can significantly decrease an interaction between SDS and asphaltenes. Adding surfactant molecules to island systems improves the interaction energy between steam and bitumen. A SB-AB system has the highest interaction energy among all six different systems containing island asphaltenes. For island asphaltenes, SDBS improved an interaction between an aqueous solution and bitumen droplets for having resin either A or B. Furthermore, the contribution of van der Waals interactions is greater than that of coulomb interactions for systems containing surfactants. Adding surfactant can increase the interfacial thickness between steam and bitumen droplets in either archipelago or island architectures, which means lower interfacial tension (IFT). Having surfactant in the steam phase provided a higher capability to emulsify bitumen droplets into the aqueous phase. According to the density profile results, island systems containing resin B (C22H30S)have a lower interfacial thickness compared to those having resin A(C22H30). In archipelago cases, no significant change in interfacial thickness was observed for similar systems with different resins.