MODELING AND SIMULATION OF PORE-SCALEMULTIPHASE FLUID FLOW AND REACTIVETRANSPORT IN FRACTURED AND POROUS MEDIA

摘要

In the subsurface, fluids play a critical role bytransporting dissolved minerals, colloids, and contaminants(sometimes over long distances); by mediating dissolutionand precipitation processes; and by enabling chemicaltransformations in solution and at mineral surfaces.Although the complex geometries of fracture apertures,fracture networks, and pore spaces may make it difficult toaccurately predict fluid flow in saturated (single-phase)subsurface systems, well-developed methods are available.The simulation of multiphase fluid flow in the subsurface ismuch more challenging because of the large density and/orviscosity ratios found in important applications (water/airin the vadose zone; water/oil, water/gas, gas/oil, and water/oil/gas in hydrocarbon reservoirs; water/aironaqueousphase liquids (nonaqueous phase liquids/dense nonaqueousphase liquids) in contaminated vadose zone systems; andgas/molten rock in volcanic systems, for example). Inaddition, the complex behavior of fluid-fluid-solid contactlines and their impact on dynamic contact angles must also be taken into account and coupled with the fluid flow. Herewe review the methods that are currently being used tosimulate pore-scale multiphase fluid flow and reactivetransport in fractured and porous media. After theintroduction, the review begins with an overview of thefundamental physics of multiphase fluids flow followed bya more detailed discussion of the complex dynamicbehavior of contact lines and contact angles, an importantbarrier to accurate pore-scale modeling and simulation. Themain part of the review focuses on five differentapproaches: pore network models, lattice gas and latticeBoltzmann methods, Monte Carlo methods, particlemethods (molecular dynamics, dissipative particledynamics, and smoothed particle hydrodynamics), andtraditional grid-based computational fluid dynamicscoupled with interface tracking and a contact anglemodel. Finally, the review closes with a discussion offuture trends and challenges.