Molecular dynamics guided design of a dual-functional viscosity reducer to break asphaltene aggregates in heavy oil

The depletion of conventional light oil reserves and the escalating global energy crisis have intensified the strategic imperative to develop unconventional heavy oil resources. However, the efficient extraction and transportation of heavy oil are severely hampered by its inherent high viscosity, primarily caused by elevated contents of asphaltenes. In this work, an oil-soluble polymeric viscosity reducer (MPPMO) was pre-designed using molecular dynamics (MD) simulations and realized by grafting polyethylene glycol monomethyl ether (PGME) onto the PMO backbone to integrate polar functionalities with a long-chain structure. Performance evaluation demonstrated that MPPMO achieves a net viscosity-reduction efficiency of 42.51%, markedly outperforming PMO (35.54%) with a relative improvement of about 20% in high-viscosity crude oil (OIL A, 17951 mPa·s) at 50 °C, while maintaining an exceptional stability over 14 h. Molecular dynamics simulations illustrate that introducing polar groups (–COOH and –O–) enables MPPMO to interact more strongly with asphaltenes than PMO, leading to the breakdown of asphaltene aggregates and viscosity reduction, while the long-chain backbone of MPPMO further inhibits their re-aggregation through steric hindrance. Therefore, these findings support a molecular-design strategy that couples long-chain backbones with multiple polar functional groups to improve the dispersion of asphaltene aggregates and enhance heavy-oil flowability.