Periodic Reporting for period 1 - Genies (Gas-water-mineral interfaces in confined spaces: unravelling and upscaling coupled hydro-geochemical processes)
Berichtszeitraum: 2022-09-01 bis 2025-02-28
The European Green Deal aims for net-zero greenhouse gas emissions by 2050, necessitating increased subsurface utilization for storage (CO2, H2) and extraction (geothermal energy). These activities induce large-scale perturbations, potentially destabilizing rock formations and contaminating groundwater. To mitigate these risks, a thorough understanding of coupled hydro-geochemical processes and reliable predictive tools is essential. Reactive transport modeling (RTM) is a key tool for tracing subsurface contaminants over extensive timescales. However, conventional RTM approaches oversimplify gas-water-mineral interactions and fail to incorporate microscale processes critical to geological environments.
Genies integrates advanced lab-on-a-chip (microfluidic) experiments with high-resolution, in operando analytical techniques to address this gap. The project focuses on mineral crystallization processes in confined porous media, specifically (i) coupled mineral dissolution/precipitation with gas generation and (ii) nucleation at the water-gas interface. These processes impact transport properties and mineral reactivity, requiring their upscaling into RTM. By generating high-fidelity experimental datasets, Genies enhances theoretical understanding of hydro-geochemical processes involving gases, leading to an improved RTM framework. The extended RTM will enable more accurate assessments of contaminant fate, thereby reducing uncertainties in subsurface storage and extraction integrity.
Genies integrates advanced lab-on-a-chip (microfluidic) experiments with high-resolution, in operando analytical techniques to address this gap. The project focuses on mineral crystallization processes in confined porous media, specifically (i) coupled mineral dissolution/precipitation with gas generation and (ii) nucleation at the water-gas interface. These processes impact transport properties and mineral reactivity, requiring their upscaling into RTM. By generating high-fidelity experimental datasets, Genies enhances theoretical understanding of hydro-geochemical processes involving gases, leading to an improved RTM framework. The extended RTM will enable more accurate assessments of contaminant fate, thereby reducing uncertainties in subsurface storage and extraction integrity.
Genies investigates mineral crystallization in confined porous media, with emphasis on gas influence on crystallization and its effects on transport properties. Three key studies were conducted:
Study 1: Crystallization in ConfinementNucleation dictates pore structure and hydraulic pathways in rock matrices. Barite (BaSO₄) commonly forms in oil, gas, and geothermal systems, reducing permeability. While its crystallization is well-documented in batch studies, compacted rock matrices present different dynamics due to slow fluid velocities and limited water volumes. Nucleation inhibition in small pores increases barite solubility (<100 nm pores), though kinetic hindrance has also been observed, necessitating further research. Using time-resolved microscopy, optical imaging, and Raman spectroscopy, barite nucleation was analyzed in bulk and nano-confined environments. Microfluidic experiments revealed nucleation scales with solution volume, consistent with classical nucleation theory, and is significantly delayed in pores <1 µm, becoming pronounced below 0.1 µm. Unexpectedly, at low supersaturation (SI < 2.2) crystallization preferentially occurred in capillaries due to high surface area, suggesting that in nanopores, thermodynamic effects dominate, whereas in micropores, geometry and surface-driven kinetics play a key role. Ongoing research focuses on gas influence on bubble formation and mineralization.
Study 2: Crystallization Kinetics of Ra-bearing BariteRadium (Ra) isotopes (e.g. 226Ra, half-life: 1600 years) are NORMs affecting oil/gas extraction, hydraulic fracturing, and geothermal systems. Ra forms (Ba,Ra)SO₄ solid solutions, impacting wastewater treatment, site remediation, and nuclear waste repositories. To elucidate the crystallization kinetics of (Ba,Ra)SO₄, microfluidic experiments monitored by time-resolved microscopy, Raman spectroscopy, and computer vision were conducted. A microfluidic mixer precipitated Ba₀.₅Ra₀.₅SO₄ at varying saturation levels. 3D Raman tomography revealed that the {210} face grew twice as fast as the {001} face, a characteristic of barite. A custom computer vision algorithm tracked crystal growth, enabling precise kinetic parameter determination. The observed growth rate followed a second-order reaction with a kinetic constant of (1.23 ± 0.09) × 10⁻¹⁰ mol m⁻² s⁻¹. These insights are being implemented in large-scale assessments of Ra migration in fractured crystalline rocks.
Study 3: Solute Transport in Partially Saturated Porous MediaSolute transport in unsaturated porous media is critical for hydrogen storage, CO2 sequestration, groundwater contamination, and radionuclide migration. A pore-scale numerical framework using the Lattice Boltzmann Method (LBM) was developed to simulate diffusion of tritiated water (HTO) and ions in variably saturated clays. The Shan-Chen LBM was applied to model spontaneous phase separation, capturing liquid/gas distributions in 3D pore structures. An equivalent solute method was developed to stabilize numerical solutions at liquid/gas interfaces with steep concentration gradients. HTO diffusion simulations in unsaturated clays (0.5 to full saturation) showed local diffusion coefficients decrease near clay surfaces, and sharp concentration jumps at liquid/gas interfaces align with Henry’s law predictions. Furthermore, Poisson-Boltzmann-Nernst-Planck equations were used to simulate ion diffusion under electrical double layer (EDL) effects. Results indicate ion diffusion decreases more than water diffusion upon desaturation, aligning with data from compacted sedimentary rocks. Ongoing work explores diffusion in chemically evolving (due to mineral crystallization) unsaturated media.
Study 1: Crystallization in ConfinementNucleation dictates pore structure and hydraulic pathways in rock matrices. Barite (BaSO₄) commonly forms in oil, gas, and geothermal systems, reducing permeability. While its crystallization is well-documented in batch studies, compacted rock matrices present different dynamics due to slow fluid velocities and limited water volumes. Nucleation inhibition in small pores increases barite solubility (<100 nm pores), though kinetic hindrance has also been observed, necessitating further research. Using time-resolved microscopy, optical imaging, and Raman spectroscopy, barite nucleation was analyzed in bulk and nano-confined environments. Microfluidic experiments revealed nucleation scales with solution volume, consistent with classical nucleation theory, and is significantly delayed in pores <1 µm, becoming pronounced below 0.1 µm. Unexpectedly, at low supersaturation (SI < 2.2) crystallization preferentially occurred in capillaries due to high surface area, suggesting that in nanopores, thermodynamic effects dominate, whereas in micropores, geometry and surface-driven kinetics play a key role. Ongoing research focuses on gas influence on bubble formation and mineralization.
Study 2: Crystallization Kinetics of Ra-bearing BariteRadium (Ra) isotopes (e.g. 226Ra, half-life: 1600 years) are NORMs affecting oil/gas extraction, hydraulic fracturing, and geothermal systems. Ra forms (Ba,Ra)SO₄ solid solutions, impacting wastewater treatment, site remediation, and nuclear waste repositories. To elucidate the crystallization kinetics of (Ba,Ra)SO₄, microfluidic experiments monitored by time-resolved microscopy, Raman spectroscopy, and computer vision were conducted. A microfluidic mixer precipitated Ba₀.₅Ra₀.₅SO₄ at varying saturation levels. 3D Raman tomography revealed that the {210} face grew twice as fast as the {001} face, a characteristic of barite. A custom computer vision algorithm tracked crystal growth, enabling precise kinetic parameter determination. The observed growth rate followed a second-order reaction with a kinetic constant of (1.23 ± 0.09) × 10⁻¹⁰ mol m⁻² s⁻¹. These insights are being implemented in large-scale assessments of Ra migration in fractured crystalline rocks.
Study 3: Solute Transport in Partially Saturated Porous MediaSolute transport in unsaturated porous media is critical for hydrogen storage, CO2 sequestration, groundwater contamination, and radionuclide migration. A pore-scale numerical framework using the Lattice Boltzmann Method (LBM) was developed to simulate diffusion of tritiated water (HTO) and ions in variably saturated clays. The Shan-Chen LBM was applied to model spontaneous phase separation, capturing liquid/gas distributions in 3D pore structures. An equivalent solute method was developed to stabilize numerical solutions at liquid/gas interfaces with steep concentration gradients. HTO diffusion simulations in unsaturated clays (0.5 to full saturation) showed local diffusion coefficients decrease near clay surfaces, and sharp concentration jumps at liquid/gas interfaces align with Henry’s law predictions. Furthermore, Poisson-Boltzmann-Nernst-Planck equations were used to simulate ion diffusion under electrical double layer (EDL) effects. Results indicate ion diffusion decreases more than water diffusion upon desaturation, aligning with data from compacted sedimentary rocks. Ongoing work explores diffusion in chemically evolving (due to mineral crystallization) unsaturated media.
Study 1: Crystallization in ConfinementMineral precipitation in porous media is essential for subsurface applications. While thermodynamic constraints are known to inhibit crystallization in <0.1 µm pores, the delayed precipitation as a function of pore size is less explored. Microfluidic experiments with defined pore geometries demonstrated that barite crystallization delay begins in 1 µm pores, scaling with pore volume. While larger pores favor mineralization, fluid exchange, pore geometry, and surface properties can alter this trend.
Study 2: Crystallization Kinetics of Ra-bearing Barite(Ba,Ra)SO₄ scales are common in geothermal, hydraulic fracturing, and oil/gas systems. Radium-226’s high radioactivity limits its study to trace levels, restricting BaₓRa₁₋ₓSO₄ compositions to x > 0.99. Genies developed a lab-on-a-chip approach coupled with computer vision to analyze (Ba,Ra)SO₄ crystal growth at elevated Ra levels. The algorithm improved experimental efficiency and statistical robustness. 3D Raman spectroscopy confirmed {210} faces grew twice as fast as {001} faces, consistent with pure barite. The growth rate adhered to a second-order reaction with a kinetic constant of (1.23 ± 0.09) × 10⁻¹⁰ mol m⁻² s⁻¹, marking a step towards AI-assisted radio-geochemical lab-on-a-chip systems.
Study 3: Solute Transport in Partially Saturated MediaThis study advances pore-scale solute transport modeling using LBM and an equivalent solute method for enhanced numerical stability. The framework accurately captures liquid/gas distributions, steep concentration gradients, and diffusion variability. Simulations validate Henry’s law predictions for HTO diffusion and reveal EDL effects on ion transport, providing novel insights into cation/anion diffusion in partially saturated media. These developments improve predictive capabilities for subsurface energy applications and environmental remediation.
Study 2: Crystallization Kinetics of Ra-bearing Barite(Ba,Ra)SO₄ scales are common in geothermal, hydraulic fracturing, and oil/gas systems. Radium-226’s high radioactivity limits its study to trace levels, restricting BaₓRa₁₋ₓSO₄ compositions to x > 0.99. Genies developed a lab-on-a-chip approach coupled with computer vision to analyze (Ba,Ra)SO₄ crystal growth at elevated Ra levels. The algorithm improved experimental efficiency and statistical robustness. 3D Raman spectroscopy confirmed {210} faces grew twice as fast as {001} faces, consistent with pure barite. The growth rate adhered to a second-order reaction with a kinetic constant of (1.23 ± 0.09) × 10⁻¹⁰ mol m⁻² s⁻¹, marking a step towards AI-assisted radio-geochemical lab-on-a-chip systems.
Study 3: Solute Transport in Partially Saturated MediaThis study advances pore-scale solute transport modeling using LBM and an equivalent solute method for enhanced numerical stability. The framework accurately captures liquid/gas distributions, steep concentration gradients, and diffusion variability. Simulations validate Henry’s law predictions for HTO diffusion and reveal EDL effects on ion transport, providing novel insights into cation/anion diffusion in partially saturated media. These developments improve predictive capabilities for subsurface energy applications and environmental remediation.