Molecular simulation study of oil-water two-phase fluid transport in shale inorganic nanopores

• The static and dynamic properties of water-nC 8 in calcite nanopores were studied. • Multilayer sticking flow happened both for single-phase nC 8 and water-nC 8 mixture. • Liquid-Liquid slip effect was observed and played positive roles for nC 8 transport. • Flow patterns change with water content and significantly affected the flow flux. • Darcy’s law is feasible to describe nC 8 when the water content is large enough. The moisture contents have significant effects on shale gas and oil adsorption and transport. In this study, the oil–water two-phase occurrence state and fluid transport in shale inorganic calcite nanopores are investigated utilizing molecular dynamics simulation. The multilayer sticking flow (negative slip) of oil and water is observed in calcite nanopores. The water bridge forms in the middle of the nanopore when water/oil ratio was high. With the decrease of water percentage, the water bridge breaks up, forming a layered structure. The flow regime changes from slug flow to laminar flow, which results in a dramatic decrease in total volume flux. The liquid–liquid slip effect between water and oil layer is observed, which has a positive effect on the enhancement of oil flow in calcite nanopore. This work reveals the two-phase configuration and flow behavior in calcite nanopores and provides the theoretical support for shale oil exploration.