Molecular insight into disassociation mechanism of tight oil in core–shell nanofluids flooding

[Display omitted] •The van der Waals gives dominant contribution to oil viscosity.•Various oil components have different contribution to oil viscosity.•The underlying dissociation mechanism was unveiled. One core–shell agent was developed to improve tight oil fluidity in micro- and nanoscale matrix channel. The dissociation effect of oil-soluble core was found playing key role, while the underlying mechanism is unclear. Here, chip displacement experiment and molecular dynamic simulation were adopted to investigate the dissociation behavior, and the microscopic mechanism was discussed in detail. Simulation results indicate the oil-soluble dissociating agent could loosen oil structure and weaken the intermolecular interaction, leading to viscosity reduction and fluidity improvement. Our work provides molecular level insight into the dissociation mechanism, and research results might have some guidance for tight oil EOR.