Molecular dynamics simulation of oil detachment from hydrophobic quartz surfaces during steam-surfactant Co-injection

In-situ recovery of bitumen involves high-temperature conditions yielded by a steam injection process, making it costly to produce, along with an extensive environmental footprint. From solvents to surfactants, additives come into play to tackle these issues efficiently. These additives can reduce a required amount of steam and increase bitumen recovery. Formulating surfactants for bitumen recovery under thermal process conditions requires solid knowledge about mechanisms and parameters incorporated into bitumen recovery. Molecular Dynamics (MD) simulation is carried out in this work to address unclear mechanisms that contribute to the bitumen recovery under a steam-anionic surfactant co-injection process. According to equilibrium MD simulation outputs, having sulfur on resin molecules can negatively affect an oil detachment process from a quartz surface due to changes in intermolecular interactions between different pairs of molecules inside a system, such as asphaltene-resin, asphaltene-asphaltene, and asphaltene-surfactant pairs. Under a flow condition, the composition of a resin fraction can change the threshold of a pumping force to detach oil from a quartz surface. During non-equilibrium MD simulation, increasing the pumping force strength from 10−5 to 10−4 Kcal/(mol.Ȧ) can improve the oil detachment process from the reservoir rock when the resin fraction contains sulfur. However, in the case of resin without sulfur, increasing the pumping force had a minor reduction in the oil detachment process. The outcomes of this paper will lay a solid foundation regarding mechanisms contributing to in-situ bitumen recovery, especially with chemical additives. Furthermore, they will provide a useful guidance for formulating chemicals applicable in the steam-chemical co-injection.