The high viscosity of heavy oil primarily stems from the aggregation of asphaltene molecules. Currently, surfactants are widely used as viscosity reducers to effectively lower the viscosity of heavy oil. This study employed molecular dynamics simulations and quantum chemical calculations to investigate the interactions between viscosity reducers⁃10 （OP⁃10）and sodium laurate (SL) with asphaltenes at different concentrations. The results show that when the molecular number of OP⁃10 (N(OP⁃10))=120 and the molecular number of SL (N(SL))=400, the composite viscosity reducer OP⁃10/SL can form micellar structures with asphaltenes. Meanwhile,the total number of hydrogen bonds in the system increases significantly from approximately 1 000 at N(OP⁃10)=30 and N(SL)=100 to about 3 800, forming a stable three dimensional hydrogen bond network. Based on visual analysis of simulation snapshots, statistics of hydrogen bond quantities and electrostatic potential distribution analysis, the viscosity reduction mechanism of this composite viscosity reducer is revealed, which provides a theoretical basis for the design and application of composite viscosity reducer systems represented by OP⁃10/SL.

A new type of gelator with π?π stacking as weak interaction force was designed and synthesized. Pyromellitic acid esters were synthesized from pyromellitic dianhydride and alcohols of different carbon chain lengths to reduce hydrogen bonding sites.Then the gel capabilities were explored in common different organic solvents.The rheological test shows that the elastic modulus of the gel system is ten folds higher than the storage modulus,indicating that the gel has good mechanical properties and exhibits typical solid?like rheological behavior.Fourier transform infrared spectroscopy,nuclear magnetic resonance spectroscopy,scanning electron microscopy and DSC results show gelators formed fibrous self?assembled aggregates in gel under driving force from π?π stacking and the van der Waals force.The formed aggregates entangle with each other and finally form a three?dimensional network structure that hinders the flow of the solvent to form the gel.