Existing strategies for hydrocarbon extraction are designed primarily based on macroscopic properties of fluids. However, recent work on shale and other tight rock formations revealed that the thermodynamics behavior and transport properties of trapped fluids deviate significantly from the bulk. In this work, using molecular dynamics simulations of methane inside nano-scale pores, we show this interfacial tension behavior could be significantly influenced by confinement effect.<br/>Local pressure is known to be anisotropic across the interfaces separating fluids in equilibrium. Tangential pressure profiles show characteristic peaks as a result of surface tension forces parallel to the interface. The layering structure, characterized by damped oscillations in local liquid density and tangential pressures, extends deep into the pore and can be a few nanometers thick. The surface tension is measured numerically using local pressures across the pore. The vapor-liquid interfacial tension is about half that of the bulk when the interface is perpendicular to the pore wall. When the vapor-liquid interface is present and parallel to the pore walls, the surface tension of that interface is varied based on the liquid saturation. The results are important for developing new strategies for hydrocarbon extraction from shale and tigh rock formations.<br/>

Nanopore wall effect on surface tension of methane

249th National Meeting (2015)

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