A Lab on a Chip Experiment for Upscaling Diffusivity of Evolving Porous Media

Abstract

Reactive transport modelling is a powerful tool to assess subsurface evolution in various energy-related applications. Upscaling, i.e., accounting for pore scale heterogeneities into larger scale analyses, remains one of the biggest challenges of reactive transport modelling. Pore scale simulations capturing the evolutions of the porous media over a wide range of Peclet and Damköhler number in combination with machine learning are foreseen as an efficient methodology for upscaling. However, the accuracy of these pore scale models needs to be tested against experiments. In this work, we developed a lab on a chip experiment with a novel micromodel design combined with operando confocal Raman spectroscopy, to monitor the evolution of porous media undergoing coupled mineral dissolution and precipitation processes due to diffusive reactive fluxes. The 3D-imaging of the porous media combined with pore scale modelling enabled the derivation of upscaled transport parameters. The chemical reaction tested involved the replacement of celestine by strontianite, whereby a net porosity increase is expected because of the smaller molar volume of strontianite. However, under our experimental conditions, the accessible porosity and consequently diffusivity decreased. We propose a transferability of the concepts behind the Verma and Pruess relationship to be applied to also describe changes of diffusivity for evolving porous media. Our results highlight the importance of calibrating pore scale models with quantitative experiments prior to simulations over a wide range of Peclet and Damköhler numbers of which results can be further used for the derivation of upscaled parameters.

Capturing the Dynamic Processes of Porosity Clogging

“…Archie's law became inadequate to predict the porosity-diffusivity evolution in response to a significant porosity decrease, showing a deviant behavior in comparison to the simulated effective diffusivities. Similar observations were reported for diffusion-driven precipitation experiments at the column-scale (Chagneau et al, 2015;Rajyaguru, 2018) and in microfluidic experiment (Poonoosamy et al, 2022), demonstrating how a simple power law function underestimates the effect of a localized porosity reduction (Chagneau et al, 2015;Deng et al, 2018;Hommel et al, 2018;Poonoosamy et al, 2022;Rajyaguru, 2018). The differences in the evolution of the porosity-diffusivity evolution observed in this study can be ascribed to different locations of nucleation and crystal growth, resulting in distinct changes in the flow pathways and thus, in the effective diffusivity at the same reduction of porosity.…”

“…There is ample evidence, however, that these empirical relationships are limited in predicting effective transport properties in response to a precipitation induced porosity reduction and pore space changes (Chagneau et al., 2015; Deng et al., 2021; Poonoosamy et al., 2020; Rajyaguru, 2018; Sabo & Beckingham, 2021). With increasing use, the combination of microstructural imaging (e.g., X‐ray micro‐CT scanning, 3D Raman imaging, positron emission tomography), pore network and pore‐scale modeling provide valuable insights for the derivation of extended REV‐scale constitutive equations (Agrawal et al., 2021; Kulenkampff et al., 2018; Menke et al., 2021; Noiriel & Soulaine, 2021; Poonoosamy et al., 2022; Roman et al., 2020; Soulaine et al., 2016). However, these extended laws have not been considered in recent modeling approaches, assessing the evolution of barrier interfaces of nuclear waste repositories (Xie et al., 2022) or geothermal systems (Tranter et al., 2021).…”

“…An alternative approach to quantify effective transport properties at the continuum-scale is the development of constitutive equations based on pore-scale modeling results (upscaling) (Deng et al, 2018;Hommel et al, 2018;Menke et al, 2021;Noiriel et al, 2012;Poonoosamy et al, 2020Poonoosamy et al, , 2022Prasianakis et al, 2020;Scheibe et al, 2015;Seigneur et al, 2019). Traditionally, empirical power-law functions are used to parameterize the effective transport properties as a function of porosity, for example, Archie's law (Archie, 1942).…”

Computational Framework for Radionuclide Migration Assessment in Clay Rocks

“…This, however, does not mean that more processes cannot be included in the model. OGS-6#iPHREEQC provides an interface to incorporate geochemical processes such as mineral dissolution/ precipitation via equilibrium or kinetic reactions (Poonoosamy et al, 2022). Further, it is possible to capture the effect of changes in the pore space due to chemical reactions and its effect over the diffusion properties of the medium, which would, in turn, have a significant effect on the mobility of radionuclides (Lu et al, 2022).…”

Precipitation-induced Geometry Evolution in Porous Media: Numerical and Experimental Insights based on New Model on Probabilistic Nucleation and Mineral Growth

“…Subsurface reactive fluid flow and solute transport is central to several pressing energy, environment, and societal challenges, including the geological storage of carbon dioxide (CO2). Mineral nucleation and growth is a prime example of interface-coupled dissolution and precipitation (ICDP) reactions giving rise to geometry evolution in porous media [1,[6][7][8][9][10][11]. When precipitation reactions are ample, crystal accumulations can dramatically reduce porosity (amount of void space) [8,10,12].…”