CO₂ activating hydrocarbon transport across nanopore throat: insights from molecular dynamics simulation

In tight oil reservoirs, nanopore throat acting as the narrowest section of fluidic channel determines the oil transport performance; injecting CO₂ is found to significantly promote the oil flow. Despite substantial efforts, the underlying transport mechanism of above phenomenon remains unclear. Employing molecular dynamics simulation, the oil transport through a nanopore throat is studied. A high energy barrier derived of conformation deformation, oil/pore interaction and Jamin effect is found to impede the oil transport. The CO₂ activating effect for oil transport is present, and a dependence on CO₂ amount is observed. The underlying mechanism was well documented from the aspects of oil swelling, interfacial tension and surface sliding. Our study provides fundamental insight into the oil transport across nanopore throat and CO₂ activating effect; the results have promising applications in enhanced oil recovery in CO₂ flooding.