Insight into surfactant adsorption performance at asphaltene surface by in-situ DPI experiment and microscopic MD simulation

In this work, the adsorption performance of tween surfactant (tween 20, tween 60 and tween 80) on asphaltene surface was investigated by both experimental and calculation methods. For experimental investigation, dual polarization interferometry (DPI) technique was utilized for in-situ measuring the adsorption mass and thickness on natural asphaltene surface. The thermodynamics Langmuir fittings indicated the mono-layer of free molecular, semi-micelle and whole-micelle adsorption for low, middle and high surfactant concentrations, respectively. The kinetic normalization corrections indicated the maximum adsorption rate at 1/2 CMC with semi-micelle form for three surfactants. For calculation insight, molecular dynamics simulation (MDS) was used for analyzing the peak intensity and interaction energy between surfactant molecular and model asphaltene of C5Pe. The RDF fitting revealed the interaction positions from 4.37 Å to 8.69 Å and the COMPASS force field showed the interaction energies from − 45.41 to − 36.34 Kcal/mol for three different surfactant-asphaltene pairs. Combined with experimental and calculation results, this work reveals the interaction forms and interaction processes between surfactant and asphaltene. Based on the mechanism analysis, tween 20 was revealed to show the most excellent interaction performance with asphaltene and can be used as potential flooding reagent for enhanced oil recovery. The results indicated that the proposed method can provide a deep insight into the interfacial behavior of surfactants at oil surface, which is of great significance in oilfield chemical development and enhanced oil recovery.