CMG: Multiphase Porous Medium Dynamics: Pore to Field Scale

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Multiphase porous medium systems occur routinely in natural and engineered systems. A motivating example class of problems for this work are porous medium systems comprised of natural materials, such as soils or aquifer materials that are occupied by multiple fluid phases. Models currently used to describe such systems do not follow naturally from pore scale representations, but rather are closed by empirical, ad hoc hysteretic relations that are intended to describe the interdependence among fluid pressures, saturations, and permeabilies. In this work, we will advance and evaluate a novel set of models based in rigorous multi-scale analysis. We will use multi-scale theory, simulation, and experiment to model phenomena associated with surface physics and chemistry that are buried in pressure-saturation relations or phenomenological aspects of current multiphase models. We will generalize standard models by the addition of interfacial contacts between solid, gas, and liquid phases. This generalization falls naturally into the class of models derived by Gray and Hassanizadeh. Closure relations represent a central piece of this work and will combine pore-scale numerical simulations, multi-scale averaging methods and analysis of scaling properties of coefficients and their consequences for macroscale model behavior, and experiments. The advanced models will be: solved with new numerical methods that generalize existing approaches, in particular new fast linear solvers with high-order accurate time-stepping algorithms; and analyzed mathematically for well-posedness with physically conceived initial-boundary conditions. Finally, we will benchmark the new models using experimental laboratory data.Multiphase subsurface flow problems present critical technological challenges to society. Current flow and transport models of porous medium systems have served vital roles in addressing the challenges, including remediation of contaminants, as well as recovery and protection of water resources. Nonetheless, advances in the fundamental models for flow and transport are needed, along with recognition and resolution of new numerical challenges associated with model developments. This work will advance the rigorous scientific and mathematical bases of such models and result in more realistic simulators for modeling transport phenomena in porous medium systems. We expect this work to lead to improved simulation of contaminant transport and recovery from groundwater systems.