A pore network model for calculation of interfacial velocities

Abstract

Two-phase flow in porous media is characterized by fluid-fluid interfaces that separate the fluid phases at the pore scale. These interfaces support pressure differences between phases, and their dynamics allow for saturation changes within the porous medium. Dynamic porescale network models allow interface dynamics to be modeled explicitly, such that each fluid-fluid interface within a network of pores is tracked explicitly in space and time. Because these models produce a detailed description of both phase and interface dynamics, results from these models can be averaged to provide values for many upscaled variables. These include nontraditional variables such as amounts of interfacial area, and volumeaveraged interfacial velocities. While these upscaled variables provide insights into the underlying dynamics of two-phase flow systems, they also allow new theories involving interfacial area to be tested directly. Results from a test of one such theory reveals that proposed constitutive equations involving interfacial velocities fail to match results from the network model for most cases considered. Therefore the macroscopic equations require additional development before they can be used for macro-scale simulations.