Nanoscale confined multicomponent hydrocarbon thermodynamic phase behavior and multiphase transport ability in nanoporous material

Multicomponent hydrocarbon transport in nanoporous material is influenced by the nanoscale thermodynamic phase behavior, heterogeneous pore structure and hydrocarbon-molecules-pore wall interaction. Little is known about the multicomponent hydrocarbon transport mechanisms in realistic 3D nanoporous material. We here propose a nanoscale pore network multiphase multicomponent hydrocarbon transport model to study multicomponent hydrocarbon thermodynamic phase behavior and transport ability across a wide range of pressure and temperature. A novel thermodynamic phase equilibrium calculation model is proposed considering the multiphase interface curvature change and phase saturation in irregular pore cross-sections. The multicomponent gas slippage effect and liquid phase boundary slip length variation with pore size are incorporated into the mode. Study results find that for low liquid phase saturations with high capillary pressure, the liquid mainly resides in the pore corners, and for high saturations with low capillary pressure it forms liquid bridges. The formation of liquid bridges, and thus ultimately decrease in gas phase transport ability, depends on the interplay of multicomponent hydrocarbon composition, pressure, temperature, the local pore shape, pore size as well as three-phase contact angle. The multicomponent hydrocarbon gas phase permeability through 3D pore network is influenced by the composition and temperature when the pore pressure is less than 15 MPa, while multicomponent gas phase permeability is unaffected by the pore pressure and temperature change at relatively high pressure (> 15 MPa). The liquid phase permeability increases with the increase of dense phase composition and the decrease of temperature at pressure less than 15 MPa. This work provides a new multicomponent hydrocarbon thermodynamic phase equilibrium model and a novel work flow of assessing multicomponent hydrocarbon multiphase transport ability in heterogeneous irregular nanoporous material.