Investigation of Different Throat Concepts for Precipitation Processes in Saturated Pore-Network Models

• Published in: Transport in porous media 2024-11, Vol.151 (14), p.2647-2692
• Main Authors: Schollenberger, Theresa, von Wolff, Lars, Bringedal, Carina, Pop, Iuliu Sorin, Rohde, Christian, Helmig, Rainer
• Format: Article
• Language: English
• Subjects: Chemical precipitation; Civil Engineering; Classical and Continuum Physics; Earth and Environmental Science; Earth Sciences; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Hydrology/Water Resources; Industrial Chemistry/Chemical Engineering; Permeability; Porous media; Scale models; Single-phase flow; Soil investigations; Soil porosity
• ISSN: 0169-3913; 1573-1634
• DOI: 10.1007/s11242-024-02125-5

The development of reliable mathematical models and numerical discretization methods is important for the understanding of salt precipitation in porous media, which is relevant for environmental problems like soil salinization. Models on the pore scale are necessary to represent local heterogeneities in precipitation and to include the influence of solution-air-solid interfaces. A pore-network model for saturated flow, which includes the precipitation reaction of salt, is presented. It is implemented in the open-source simulator DuMu X . In this paper, we restrict ourselves to one-phase flow as a first step. Since the throat transmissibilities determine the flow behaviour in the pore network, different concepts for the decreasing throat transmissibility due to precipitation are investigated. We consider four concepts for the amount of precipitation in the throats. Three concepts use information from the adjacent pore bodies, and one employs a pore-throat model obtained by averaging the resolved pore-scale model in a thin-tube. They lead to different permeability developments, which are caused by the different distribution of the precipitate between the pore bodies and throats. We additionally apply two different concepts for the calculation of the transmissibility. One obtains the precipitate distribution from analytical assumptions, the other from a geometric minimization principle using a phase-field evolution equation. The two concepts do not show substantial differences for the permeability development as long as simple pore-throat geometries are used. Finally, advantages and disadvantages of the concepts are discussed in the context of the considered physical problem and a reasonable effort for the implementation and computational costs. Article Highlights Presentation of a pore-network model for single-phase flow with salt precipitation including pore-space alterations Different concepts to calculate the amount of precipitation in throats and the throat transmissibility are presented Between the concepts large differences in the permeability and precipitation distribution are observed in the network