Uniqueness of Specific Interfacial Area-Capillary Pressure-Saturation Relationship Under Non-Equilibrium Conditions in Two-Phase Porous Media Flow

作者：Joekar Niasar Vahid^*; Hassanizadeh S Majid

来源：Transport in Porous Media, 2012, 94(2): 465-486.

DOI：10.1007/s11242-012-9958-3

• Two-phase flow
• Interfacial area
• Hysteresis
• Dynamic pore network
• Non-equilibrium

The capillary pressure-saturation (P (c)-S (w)) relationship is one of the central constitutive relationships used in two-phase flow simulations. There are two major concerns regarding this relation. These concerns are partially studied in a hypothetical porous medium using a dynamic pore-network model called DYPOSIT, which has been employed and extended for this study: (a) P (c)-S (w) relationship is measured empirically under equilibrium conditions. It is then used in Darcy-based simulations for all dynamic conditions. This is only valid if there is a guarantee that this relationship is unique for a given flow process (drainage or imbibition) independent of dynamic conditions; (b) It is also known that P (c)-S (w) relationship is flow process dependent. Depending on drainage and imbibition, different curves can be achieved, which are referred to as "hysteresis". A thermodynamically derived theory (Hassanizadeh and Gray, Water Resour Res 29: 3389-3904, 1993a) suggests that, by introducing a new state variable, called the specific interfacial area (a (nw), defined as the ratio of fluid-fluid interfacial area to the total volume of the domain), it is possible to define a unique relation between capillary pressure, saturation, and interfacial area. This study investigates these two aspects of capillary pressure-saturation relationship using a dynamic pore-network model. The simulation results imply that P (c)-S (w) relation not only depends on flow process (drainage and imbibition) but also on dynamic conditions for a given flow process. Moreover, this study attempts to obtain the first preliminary insig

• 出版日期2012-9