Insights into Asphaltene Adsorption on Sandstone Surface by Experiment and Simulation: Performance and Mechanism Investigation

Asphaltene adsorption at rock surfaces has important effects on enhanced oil recovery (EOR) in the petroleum industry. In this work, the adsorption interaction of asphaltene with sandstone rock of albite and quartz is investigated to derive experimental and simulation insights. By macroscopic experimental investigation, the interaction performances were evaluated by thermodynamic models of the Langmuir and Freundlich fittings and kinetic models of pseudo-first-order (PFO) and pseudo-second-order (PSO) fittings. The results indicate monolayer molecular asphaltene adsorption for both albite and quartz, but "fast adsorption–slow desorption" is observed for albite and "slow adsorption–fast desorption" for quartz. Meanwhile, albite shows a larger adsorption capacity and stronger adsorption spontaneity with the results of qm(albite 1#) = 2.58 mg g–1 > qm(quartz 1#) = 1.22 mg g–1 and ΔGalbite 1 = −2.40 kJ mol–1 < ΔGquartz 1 = −0.97 J mol–1. By microscopic molecular dynamic simulation (MDS) simulation, the interaction performances were studied for three asphaltene molecules of archipelago-type, island-type, and resin-type. Albite rock shows much higher system stability than quartz, with a more negative final energy of ΔEalbite–quartz = −59 kJ mol–1, and archipelago asphaltene shows the smallest adsorption equilibrium energy, with Eads(archipelago) = −104 < Eads(island) = −71 < Eads(resin) = −58 kJ mol–1 for albite adsorption and Eads(archipelago) = −45 < Eads(island) = −35 ∼ Eads(resin) = −35 kJ mol–1 for quartz adsorption. The interaction mechanism was illustrated by molecular orientation and force dominance for asphaltene adsorption, which "lie sideways" at low concentrations but "stand upright" at high concentrations. This work provided information on the performance and mechanism of asphaltene adsorption at rock surfaces, which is of great significance in reservoir exploitation and enhanced oil recovery.