The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Michael A. Celia - One of the best experts on this subject based on the ideXlab platform.
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applicability of averaged concentrations in determining Geochemical Reaction rates in heterogeneous porous media
American Journal of Science, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:This work examines the applicability of averaged concentrations, a mathematical analog of field-measured solute concentrations averaged over a large number of pores, in determining mineral Reaction rates in heterogeneous porous media. Pore-scale network models were used to represent sandstones with anorthite and kaolinite as reactive minerals that are heterogeneously distributed in space. Reaction rates calculated from averaged concentrations were compared to true Reaction rates that take into account variabilities in individual pore properties. Simulations were run under the highly acidic conditions relevant to geological CO2 sequestration in deep brine formations under various mineralogical and flow conditions. Results show that, under conditions where incomplete mixing arises, the averaged concentrations and analogously the field-measured concentrations, do not accurately reflect Reaction progress. Over the length scale of several millimeters, the anorthite dissolution rates can be overestimated by a factor of three. For kaolinite, due to its highly nonlinear Reaction rate law, even the Reaction direction may be incorrectly determined, with precipitation predicted as dissolution. The extent of errors introduced depends on the extent of incomplete mixing. Conditions that homogenize the concentration fields, such as small reactive mineral clusters, abundant reactive minerals, and very fast or very slow flow rates, minimize errors introduced from averaging. These results indicate that the averaging scheme may partly contribute to the often-cited laboratory-field rate discrepancy and have important implications for the interpretation of concentration data obtained from field investigation.
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reply to comment on upscaling Geochemical Reaction rates using pore scale network modeling by peter c lichtner and qinjun kang
Advances in Water Resources, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:Our paper "Upscaling Geochemical Reaction rates usingpore-scale network modeling" presents a novel application of pore-scalenetwork modeling to upscale mineral dissolution and precipitationReaction rates from the pore scale to the continuum scale, anddemonstrates the methodology by analyzing the scaling behavior ofanorthite and kaolinite Reaction kinetics under conditions related to CO2sequestration. We conclude that under highly acidic conditions relevantto CO2 sequestration, the traditional continuum-based methodology may notcapture the spatial variation in concentrations from pore to pore, andscaling tools may be important in correctly modeling reactive transportprocesses in such systems. This work addresses the important butdifficult question of scaling mineral dissolution and precipitationReaction kinetics, which is often ignored in fields such as geochemistry,water resources, and contaminant hydrology. Although scaling of physicalprocesses has been studied for almost three decades, very few studieshave examined the scaling issues related to chemical processes, despitetheir importance in governing the transport and fate of contaminants insubsurface systems.
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Reply to “Comment on upscaling Geochemical Reaction rates using pore-scale network modeling” by Peter C. Lichtner and Qinjun Kang
Advances in Water Resources, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:Our paper "Upscaling Geochemical Reaction rates usingpore-scale network modeling" presents a novel application of pore-scalenetwork modeling to upscale mineral dissolution and precipitationReaction rates from the pore scale to the continuum scale, anddemonstrates the methodology by analyzing the scaling behavior ofanorthite and kaolinite Reaction kinetics under conditions related to CO2sequestration. We conclude that under highly acidic conditions relevantto CO2 sequestration, the traditional continuum-based methodology may notcapture the spatial variation in concentrations from pore to pore, andscaling tools may be important in correctly modeling reactive transportprocesses in such systems. This work addresses the important butdifficult question of scaling mineral dissolution and precipitationReaction kinetics, which is often ignored in fields such as geochemistry,water resources, and contaminant hydrology. Although scaling of physicalprocesses has been studied for almost three decades, very few studieshave examined the scaling issues related to chemical processes, despitetheir importance in governing the transport and fate of contaminants insubsurface systems.
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Upscaling Geochemical Reaction rates using pore-scale network modeling
Advances in Water Resources, 2006Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:Geochemical Reaction rate laws are often measured using crushed minerals in well-mixed laboratory systems that are designed to eliminate mass transport limitations. Such rate laws are often used directly in reactive transport models to predict the Reaction and transport of chemical species in consolidated porous media found in subsurface environments. Due to the inherent heterogeneities of porous media, such use of lab-measured rate laws may introduce errors, leading to a need to develop methods for upscaling Reaction rates. In this work, we present a methodology for using pore-scale network modeling to investigate scaling effects in Geochemical Reaction rates. The reactive transport processes are simulated at the pore scale, accounting for heterogeneities of both physical and mineral properties. Mass balance principles are then used to calculate Reaction rates at the continuum scale. To examine the scaling behavior of Reaction kinetics, these continuum-scale rates from the network model are compared to the rates calculated by directly using laboratory-measured Reaction rate laws and ignoring pore-scale heterogeneities. In this work, this methodology is demonstrated by upscaling anorthite and kaolinite Reaction rates under simulation conditions relevant to geological CO2 sequestration. Simulation results show that under conditions with CO2 present at high concentrations, pore-scale concentrations of reactive species and Reaction rates vary spatially by orders of magnitude, and the scaling effect is significant. With a much smaller CO2 concentration, the scaling effect is relatively small. These results indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. This work demonstrates the use of pore-scale network modeling as a valuable research tool for examining upscaling of Geochemical kinetics. The pore-scale model allows the effects of pore-scale heterogeneities to be integrated into system behavior at multiple scales, thereby identifying important factors that contribute to the scaling effect. � 2005 Elsevier Ltd. All rights reserved.
Catherine A. Peters - One of the best experts on this subject based on the ideXlab platform.
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Up-Scaling Geochemical Reaction Rates for Carbon Dioxide (CO2) in Deep Saline Aquifers
2013Co-Authors: Catherine A. PetersAbstract:Geochemical Reactions in deep subsurface environments are complicated by the consolidated nature and mineralogical complexity of sedimentary rocks. Understanding the kinetics of these Reactions is critical to our ability to make long-term predictions about subsurface processes such as pH buffering, alteration in rock structure, permeability changes, and formation of secondary precipitates. In this project, we used a combination of experiments and numerical simulation to bridge the gap between our knowledge of these Reactions at the lab scale and rates that are meaningful for modeling reactive transport at core scales. The focus is on acid-driven mineral dissolution, which is specifically relevant in the context of CO2-water-rock interactions in geological sequestration of carbon dioxide. The project led to major findings in three areas. First, we modeled reactive transport in pore-network systems to investigate scaling effects in Geochemical Reaction rates. We found significant scaling effects when CO2 concentrations are high and Reaction rates are fast. These findings indicate that the increased acidity associated with geological sequestration can generate conditions for which proper scaling tools are yet to be developed. Second, we used mathematical modeling to investigate the extent to which SO2, if co-injected with CO2, would acidify formation brines. We found that theremore » exist realistic conditions in which the impact on brine acidity will be limited due to diffusion rate-limited SO2 dissolution from the CO2 phase, and the subsequent pH shift may also be limited by the lack of availability of oxidants to produce sulfuric acid. Third, for three Viking sandstones (Alberta sedimentary basin, Canada), we employed backscattered electron microscopy and energy dispersive X-ray spectroscopy to statistically characterize mineral contact with pore space. We determined that for reactive minerals in sedimentary consolidated rocks, abundance alone is not a good predictor of mineral accessible surface area, and should not be used in reactive transport modeling. Our work showed that Reaction rates would be overestimated by three to five times.« less
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upscaling Geochemical Reaction rates accompanying acidic co2 saturated brine flow in sandstone aquifers
Water Resources Research, 2011Co-Authors: Daesang Kim, Catherine A. Peters, W B LindquistAbstract:[1] Network flow models were used to simulate the flow of CO2-saturated brine in the pore networks corresponding to three different sandstones. The simulations were used to study upscaling of anorthite and kaolinite Reaction rates from pore to core scales. Unique to our simulations is the use of computed tomography to capture the mineral distribution in the samples as well as the sample pore network. The upscaled Reaction rates determined from these simulations incorporate mass balance principles and microscale Reaction rate laws and capture the physical, mineral, and flow heterogeneities in the network. These upscaled rates were compared with upscaled rates predicted by a continuum model and by a volume-averaged-concentration method. For the anorthite Reaction, which remains far from equilibrium, the volume-averaged Reaction rate exceeded the Reaction rate of the network model by 18% to 46%. While the continuum model rate also exceeded the network model rate by −1% to 53%, its predicted values were generally better than the volume-averaged method. The kaolinite Reaction is near equilibrium and is heavily influenced by the form of the microscale rate law in the precipitation regime. Three alternate rate laws were tested, which produced significantly different predictions for the bulk Reaction rates. For all three rate laws, continuum and volume-averaged Reaction rates incorrectly predicted the magnitude of the kaolinite Reaction rate (disagreements of −700% to 55%), and the predicted Reaction type, dissolution versus precipitation, was also often opposite to that of the network model. Finally, for both anorthite and kaolinite, all upscaled Reaction rates showed significant flow rate dependence.
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applicability of averaged concentrations in determining Geochemical Reaction rates in heterogeneous porous media
American Journal of Science, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:This work examines the applicability of averaged concentrations, a mathematical analog of field-measured solute concentrations averaged over a large number of pores, in determining mineral Reaction rates in heterogeneous porous media. Pore-scale network models were used to represent sandstones with anorthite and kaolinite as reactive minerals that are heterogeneously distributed in space. Reaction rates calculated from averaged concentrations were compared to true Reaction rates that take into account variabilities in individual pore properties. Simulations were run under the highly acidic conditions relevant to geological CO2 sequestration in deep brine formations under various mineralogical and flow conditions. Results show that, under conditions where incomplete mixing arises, the averaged concentrations and analogously the field-measured concentrations, do not accurately reflect Reaction progress. Over the length scale of several millimeters, the anorthite dissolution rates can be overestimated by a factor of three. For kaolinite, due to its highly nonlinear Reaction rate law, even the Reaction direction may be incorrectly determined, with precipitation predicted as dissolution. The extent of errors introduced depends on the extent of incomplete mixing. Conditions that homogenize the concentration fields, such as small reactive mineral clusters, abundant reactive minerals, and very fast or very slow flow rates, minimize errors introduced from averaging. These results indicate that the averaging scheme may partly contribute to the often-cited laboratory-field rate discrepancy and have important implications for the interpretation of concentration data obtained from field investigation.
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reply to comment on upscaling Geochemical Reaction rates using pore scale network modeling by peter c lichtner and qinjun kang
Advances in Water Resources, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:Our paper "Upscaling Geochemical Reaction rates usingpore-scale network modeling" presents a novel application of pore-scalenetwork modeling to upscale mineral dissolution and precipitationReaction rates from the pore scale to the continuum scale, anddemonstrates the methodology by analyzing the scaling behavior ofanorthite and kaolinite Reaction kinetics under conditions related to CO2sequestration. We conclude that under highly acidic conditions relevantto CO2 sequestration, the traditional continuum-based methodology may notcapture the spatial variation in concentrations from pore to pore, andscaling tools may be important in correctly modeling reactive transportprocesses in such systems. This work addresses the important butdifficult question of scaling mineral dissolution and precipitationReaction kinetics, which is often ignored in fields such as geochemistry,water resources, and contaminant hydrology. Although scaling of physicalprocesses has been studied for almost three decades, very few studieshave examined the scaling issues related to chemical processes, despitetheir importance in governing the transport and fate of contaminants insubsurface systems.
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Reply to “Comment on upscaling Geochemical Reaction rates using pore-scale network modeling” by Peter C. Lichtner and Qinjun Kang
Advances in Water Resources, 2007Co-Authors: Catherine A. Peters, Michael A. CeliaAbstract:Our paper "Upscaling Geochemical Reaction rates usingpore-scale network modeling" presents a novel application of pore-scalenetwork modeling to upscale mineral dissolution and precipitationReaction rates from the pore scale to the continuum scale, anddemonstrates the methodology by analyzing the scaling behavior ofanorthite and kaolinite Reaction kinetics under conditions related to CO2sequestration. We conclude that under highly acidic conditions relevantto CO2 sequestration, the traditional continuum-based methodology may notcapture the spatial variation in concentrations from pore to pore, andscaling tools may be important in correctly modeling reactive transportprocesses in such systems. This work addresses the important butdifficult question of scaling mineral dissolution and precipitationReaction kinetics, which is often ignored in fields such as geochemistry,water resources, and contaminant hydrology. Although scaling of physicalprocesses has been studied for almost three decades, very few studieshave examined the scaling issues related to chemical processes, despitetheir importance in governing the transport and fate of contaminants insubsurface systems.
Jinyoung Park - One of the best experts on this subject based on the ideXlab platform.
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The Use of the Surface Roughness Value to Quantify the Extent of Supercritical CO2 Involved Geochemical Reaction at a CO2 Sequestration Site
Applied Sciences, 2017Co-Authors: Jinyoung Park, Kyoungbae Baek, Minhee Lee, Chul-woo Chung, Sookyun WangAbstract:Changes in the physical properties of the supercritical CO2 (scCO2) reservoir rock is one of the most important factors in controlling the storage safety at a scCO2 sequestration site. According to recent studies, it is probable that Geochemical Reactions influence changes in the rock properties after a CO2 injection in the subsurface, but quantitative data that reveal the interrelationship of the factors involved and the parameters needed to evaluate the extent of scCO2-rock-groundwater Reactions have not yet been presented. In this study, the potential for employing the surface roughness value (SRRMS) to quantify the extent of the scCO2 involved Reaction was evaluated by lab-scale experiments. For a total of 150 days of a simulation of the scCO2-sandstone-groundwater Reaction at 100 bar and 50 °C, the trends in changes in the physical rock properties, pH change, and cation concentration change followed similar logarithmic patterns that were significantly correlated with the logarithmic increase in the SRRMS value. These findings suggest that changes in surface roughness can quantify the extent of the Geochemical weathering process and can be used to evaluate leakage safety due to the progressive changes in rock properties at scCO2 storage sites.
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physical property changes of sandstones in korea derived from the supercritical co2 sandstone groundwater Geochemical Reaction under co2 sequestration condition
Geosciences Journal, 2015Co-Authors: Jinyoung Park, Kyoungbae Baek, Sookyun WangAbstract:Laboratory experiments and calculation of the dissolution constant were performed to investigate the physical property changes of sandstones in Korea resulting from the Geochemical Reaction of CO2 under sequestration conditions. To simulate the sub-surface storage condition (100 bar and 50 °C), the high pressurized stainless cell and chamber were used and the supercritical CO2 fluid was injected into the cell (or the chamber) by the syringe pump and the pressure regulator. Sandstone slabs and cores were used for the experiments of the supercritical CO2-sandstone‒groundwater Reaction. Results of SEM/EDS and SPM analyses showed that the surface roughness of the slab increased and the precipitation of calcite, halite, and Ca-rich silicate minerals on the sandstone slab occurred during 60 days Reaction, suggesting the Geochemical weathering process, as a result of CO2 injection, directly leads to property changes of sandstones in a short time. The average porosity of sandstone cores as increased 8.8% with the corresponding decreases in the dry density, P and S wave velocity, dynamic Young’s modulus, and the uniaxial compression strength, indicating that the trend of property changes for the sandstone was well fitted to the first-order Reaction curve. The average first-order dissolution constant (K 1) of sandstones, calculated by using the loss of sandstone mass during the Reaction time was 0.0000846 day−1. The K 1 values will be useful for estimating the dissolution process of sandstones originated from the supercritical CO2-sandstone‒groundwater Reaction while the CO2 was injected into the sub-surface.
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Investigation of the Relationship between CO2 Reservoir Rock Property Change and the Surface Roughness Change Originating from the Supercritical CO2-Sandstone-groundwater Geochemical Reaction at CO2 Sequestration Condition
Energy Procedia, 2015Co-Authors: Minhee Lee, Sookyun Wang, Seyoon Kim, Jinyoung ParkAbstract:Abstract Laboratory experiments were performed to investigate the property change of sandstones, resulting from scCO2-rock-groundwater Reaction for 150 days under CO2 sequestration conditions. The average surface roughness value (SRrms) increased more than 3.5 times during early 90 days, suggesting that the weathering process of sandstone occurs in the early Reaction time after CO2 injection. The average porosity of sandstones increased by 8.8% and P wave velocity decreased by 5.7%. The trend of rock property change and SRrms change showed in a logarithmic manner, indicating that the physical property change of reservoir rocks directly comes from CO2 related Geochemical Reaction.
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Physical property changes of sandstones in Korea derived from the supercritical CO2-sandstone‒groundwater Geochemical Reaction under CO2 sequestration condition
Geosciences Journal, 2014Co-Authors: Jinyoung Park, Kyoungbae Baek, Minhee Lee, Sookyun WangAbstract:Laboratory experiments and calculation of the dissolution constant were performed to investigate the physical property changes of sandstones in Korea resulting from the Geochemical Reaction of CO2 under sequestration conditions. To simulate the sub-surface storage condition (100 bar and 50 °C), the high pressurized stainless cell and chamber were used and the supercritical CO2 fluid was injected into the cell (or the chamber) by the syringe pump and the pressure regulator. Sandstone slabs and cores were used for the experiments of the supercritical CO2-sandstone‒groundwater Reaction. Results of SEM/EDS and SPM analyses showed that the surface roughness of the slab increased and the precipitation of calcite, halite, and Ca-rich silicate minerals on the sandstone slab occurred during 60 days Reaction, suggesting the Geochemical weathering process, as a result of CO2 injection, directly leads to property changes of sandstones in a short time. The average porosity of sandstone cores as increased 8.8% with the corresponding decreases in the dry density, P and S wave velocity, dynamic Young’s modulus, and the uniaxial compression strength, indicating that the trend of property changes for the sandstone was well fitted to the first-order Reaction curve. The average first-order dissolution constant (K 1) of sandstones, calculated by using the loss of sandstone mass during the Reaction time was 0.0000846 day−1. The K 1 values will be useful for estimating the dissolution process of sandstones originated from the supercritical CO2-sandstone‒groundwater Reaction while the CO2 was injected into the sub-surface.
Sookyun Wang - One of the best experts on this subject based on the ideXlab platform.
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The Use of the Surface Roughness Value to Quantify the Extent of Supercritical CO2 Involved Geochemical Reaction at a CO2 Sequestration Site
Applied Sciences, 2017Co-Authors: Jinyoung Park, Kyoungbae Baek, Minhee Lee, Chul-woo Chung, Sookyun WangAbstract:Changes in the physical properties of the supercritical CO2 (scCO2) reservoir rock is one of the most important factors in controlling the storage safety at a scCO2 sequestration site. According to recent studies, it is probable that Geochemical Reactions influence changes in the rock properties after a CO2 injection in the subsurface, but quantitative data that reveal the interrelationship of the factors involved and the parameters needed to evaluate the extent of scCO2-rock-groundwater Reactions have not yet been presented. In this study, the potential for employing the surface roughness value (SRRMS) to quantify the extent of the scCO2 involved Reaction was evaluated by lab-scale experiments. For a total of 150 days of a simulation of the scCO2-sandstone-groundwater Reaction at 100 bar and 50 °C, the trends in changes in the physical rock properties, pH change, and cation concentration change followed similar logarithmic patterns that were significantly correlated with the logarithmic increase in the SRRMS value. These findings suggest that changes in surface roughness can quantify the extent of the Geochemical weathering process and can be used to evaluate leakage safety due to the progressive changes in rock properties at scCO2 storage sites.
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physical property changes of sandstones in korea derived from the supercritical co2 sandstone groundwater Geochemical Reaction under co2 sequestration condition
Geosciences Journal, 2015Co-Authors: Jinyoung Park, Kyoungbae Baek, Sookyun WangAbstract:Laboratory experiments and calculation of the dissolution constant were performed to investigate the physical property changes of sandstones in Korea resulting from the Geochemical Reaction of CO2 under sequestration conditions. To simulate the sub-surface storage condition (100 bar and 50 °C), the high pressurized stainless cell and chamber were used and the supercritical CO2 fluid was injected into the cell (or the chamber) by the syringe pump and the pressure regulator. Sandstone slabs and cores were used for the experiments of the supercritical CO2-sandstone‒groundwater Reaction. Results of SEM/EDS and SPM analyses showed that the surface roughness of the slab increased and the precipitation of calcite, halite, and Ca-rich silicate minerals on the sandstone slab occurred during 60 days Reaction, suggesting the Geochemical weathering process, as a result of CO2 injection, directly leads to property changes of sandstones in a short time. The average porosity of sandstone cores as increased 8.8% with the corresponding decreases in the dry density, P and S wave velocity, dynamic Young’s modulus, and the uniaxial compression strength, indicating that the trend of property changes for the sandstone was well fitted to the first-order Reaction curve. The average first-order dissolution constant (K 1) of sandstones, calculated by using the loss of sandstone mass during the Reaction time was 0.0000846 day−1. The K 1 values will be useful for estimating the dissolution process of sandstones originated from the supercritical CO2-sandstone‒groundwater Reaction while the CO2 was injected into the sub-surface.
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Investigation of the Relationship between CO2 Reservoir Rock Property Change and the Surface Roughness Change Originating from the Supercritical CO2-Sandstone-groundwater Geochemical Reaction at CO2 Sequestration Condition
Energy Procedia, 2015Co-Authors: Minhee Lee, Sookyun Wang, Seyoon Kim, Jinyoung ParkAbstract:Abstract Laboratory experiments were performed to investigate the property change of sandstones, resulting from scCO2-rock-groundwater Reaction for 150 days under CO2 sequestration conditions. The average surface roughness value (SRrms) increased more than 3.5 times during early 90 days, suggesting that the weathering process of sandstone occurs in the early Reaction time after CO2 injection. The average porosity of sandstones increased by 8.8% and P wave velocity decreased by 5.7%. The trend of rock property change and SRrms change showed in a logarithmic manner, indicating that the physical property change of reservoir rocks directly comes from CO2 related Geochemical Reaction.
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Physical property changes of sandstones in Korea derived from the supercritical CO2-sandstone‒groundwater Geochemical Reaction under CO2 sequestration condition
Geosciences Journal, 2014Co-Authors: Jinyoung Park, Kyoungbae Baek, Minhee Lee, Sookyun WangAbstract:Laboratory experiments and calculation of the dissolution constant were performed to investigate the physical property changes of sandstones in Korea resulting from the Geochemical Reaction of CO2 under sequestration conditions. To simulate the sub-surface storage condition (100 bar and 50 °C), the high pressurized stainless cell and chamber were used and the supercritical CO2 fluid was injected into the cell (or the chamber) by the syringe pump and the pressure regulator. Sandstone slabs and cores were used for the experiments of the supercritical CO2-sandstone‒groundwater Reaction. Results of SEM/EDS and SPM analyses showed that the surface roughness of the slab increased and the precipitation of calcite, halite, and Ca-rich silicate minerals on the sandstone slab occurred during 60 days Reaction, suggesting the Geochemical weathering process, as a result of CO2 injection, directly leads to property changes of sandstones in a short time. The average porosity of sandstone cores as increased 8.8% with the corresponding decreases in the dry density, P and S wave velocity, dynamic Young’s modulus, and the uniaxial compression strength, indicating that the trend of property changes for the sandstone was well fitted to the first-order Reaction curve. The average first-order dissolution constant (K 1) of sandstones, calculated by using the loss of sandstone mass during the Reaction time was 0.0000846 day−1. The K 1 values will be useful for estimating the dissolution process of sandstones originated from the supercritical CO2-sandstone‒groundwater Reaction while the CO2 was injected into the sub-surface.
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study for the Geochemical Reaction of ca feldspar amphibole and olivine with supercritical co_2 and brine on the co_2 sequestration condition
Economic and Environmental Geology, 2011Co-Authors: Hyunmin Kang, Sanghee Park, Minho Park, Sookyun WangAbstract:The lab scale experiments to investigate the Geochemical Reaction among supercritical -mineral-brine which occurs at sequestration sites were performed. High pressurized cell system (l00 bar and ) was designed to create supercritical in the cell, simulating the sub-surface storage site. From the high pressurized cell experiment, the surface changes of Ca-feldspar, amphibole (tremolite) and olivine, resulted from the supercritical -mineral-brine Reaction, were observed and the dissolution of minerals into the brine was also investigated. The mineral slabs were polished and three locations on the surface were randomly selected for the image analysis of SPM and the surface roughness value (SRV) of those locations were calculated to quantify the change of mineral surface for 30 days. At a certain time interval, SPM images and SRVs of the same mineral surface were acquired. The secondary minerals precipitated on the mineral surfaces were also analyzed on SEM/EDS after the experiment. From the experiments, the average SRV of Ca-feldspar increased from 2.77 nm to 20.87 nm for 30 days, suggesting that the dissolution of Ca-feldspar occurs in active when the feldspars contact with supercritical and brine. For the amphibole, the average SRV increased from 2.54 nm to 8.31 nm and for the olivine from 0.77 nm to 11.03 run. For the Ca-feldspar, , , , , and were dissolved in the highest order and , , and for the amphibole. Fe (or Mg) - oxides were precipitated as the secondary minerals on the surfaces of amphibole and olivine after 30 days Reaction. Results suggested that , and rich minerals would be significantly weathered when it contacts with the supercritical and brine at sequestration sites.
Vincent Lagneau - One of the best experts on this subject based on the ideXlab platform.
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Uncertainty quantification for uranium production in mining exploitation by In Situ Recovery
Computational Geosciences, 2021Co-Authors: Jean Langanay, Valérie Langlais, Thomas Romary, Xavier Freulon, Gwenaele Petit, Vincent LagneauAbstract:Uranium In Situ Recovery (ISR) is based on the direct leaching of the uranium ore in the deposit by a mining solution. Fluid flow and Geochemical Reaction in the reservoir are difficult to predict due to geological, petrophysical and Geochemical uncertainties. The reactive transport simulation code used to model ISR is very sensitive to the spatial distribution of physical and chemical properties of the deposit. Stochastic geostatistical models are used to represent the uncertainty on the spatial distribution of geological properties. The direct propagation of geological uncertainties by multiple ISR mining simulations is intractable in an industrial context. The CPU time needed to perform one ISR numerical simulation is too heavy. This work presents a way to propagate geological uncertainties into uranium production uncertainties at a reduced computational cost, thanks to a scenario reduction method. A subset of geostatistical simulations is built to approximate the variability of a larger set. The selection is obtained using a proxy of reactive transport simulation. The main contribution of this work is the development of the proxy, which is based on an artificial mineral exploitation that has common properties with uraninite. It allows the discrimination of geostatistical realizations in terms of potential uranium production. Then, the ISR simulation carried out with the selected geostatistical realizations gives a good approximation of the uranium production variability over the whole set of geostatistical simulations. This approximation is then used to quantify the uncertainties on the uranium production. The proposed approach is assessed on real case studies.
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Evaluation of the solubility constants of the hydrated solid phases in the H2O-Al2O3-SO3 ternary system
The European Physical Journal. Special Topics, 2017Co-Authors: Angélique Teyssier, Vincent Lagneau, Schmitt Jean-michel, Jean-jacques Counioux, Christelle GoutaudierAbstract:During the acid processing of aluminosilicate ores, the precipitation of a solid phase principally consisting of hydrated aluminium hydroxysulfates may be observed. The experimental study of the H2O-Al2O3-SO3 ternary system at 25 ◦ C and 101 kPa enabled to describe the solid-liquid equilibria and to identify the nature, the composition and the solubility of the solid phases which may form during the acid leaching. To predict the appearance of these aluminium hydroxysulfates in more complex systems, their solubility constants were calculated by modelling the experimental solubility results, using a Geochemical Reaction modelling software, CHESS. A model for non-ideality correction, based on the B-dot equation, was used as it was suitable for the considered ion concentration range. The solubility constants of three out of four solid phases were calculated: 104.08 for jurbanite (Al(SO4)(OH).5H2O), 1028.09 for the solid T (Al8(SO4)5(OH)14.34H2O) and 1027.28 for the solid V (Al10(SO4)3(OH)24.20H2O). However the activity correction model was not suitable to determine the solubility constant of alunogen (Al2(SO4)3.15.8H2O), as the ion concentrations of the mixtures were too high and beyond the allowable limits of the model. Another ionic activity correction model, based on the Pitzer equation for example, must be applied to calculate the solubility constant of alunogen.
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Kinetic reactive transport modelling of column tests for uranium In Situ Recovery (ISR) mining
Applied Geochemistry, 2014Co-Authors: Rose Ben Simon, Vincent Lagneau, Médard Thiry, Jean-michel Schmitt, Valérie Langlais, Michel BélièresAbstract:Numerical modelling of the interaction between solution and rock is examined in order to improve the management of U In Situ Recovery (ISR) mining. Two ‘classical’ types of leaching experiments were performed: (1) tests in batch reactors; and (2) extraction in flow-through columns. A comprehensive interpretation of the complete leaching test results (mineralogy of the samples and chemical analysis of leachates) led to the development of a conceptual model with reasonable assumptions about dissolution and precipitation Reactions during the acid leach of the columns. This conceptual model was tested and validated by numerical modelling of the two types of laboratory experiments. Batch experiments were simulated with the Geochemical code CHESS in order to model the leachate solutions and to calibrate the Geochemical Reaction paths and their kinetic laws. The Geochemical models with kinetics successfully simulated the trend of leachate’ chemistry in the two types of experimental tests (batch and column). They resulted in a proposal of a 1D hydroGeochemical transport model of the ISR process at laboratory-scale. Furthermore, a sensitivity analysis conducted on the 1D-calibrated model made it possible (1) to determine factors controlling leaching Reactions; and (2) to quantify their respective influence on the uranium recovery in terms of acid consumption and leachate volume to treat in the plant.
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Precipitation of lead-zinc ores in the Mississipi Valley-type deposit at Trèves, Cévennes region of southern France
Geofluids, 2006Co-Authors: David Leach, Vincent Lagneau, J.c Macquar, J. Leventhal, P. Emsbo, W. PremoAbstract:The Trèves zinc-lead deposit is one of several Mississippi Valley-type (MVT) deposits in the Cévennes region of southern France. Fluid inclusion studies show that the ore was deposited at temperatures between approximately 80 and 150°C from a brine that derived its salinity mainly from the evaporation of seawater past halite saturation. Lead isotope studies suggest that the metals were extracted from local basement rocks. Sulfur isotope data and studies of organic matter indicate that the reduced sulfur in the ores was derived from the reduction of Mesozoic marine sulfate by thermochemical sulfate reduction or bacterially mediated processes at a different time or place from ore deposition. The large range of δ34S values determined for the minerals in the deposit (12.2-19.2‰ for barite, 3.8-13.8‰ for sphalerite and galena, and 8.7 to −21.2‰ for pyrite), are best explained by the mixing of fluids containing different sources of sulfur. Geochemical Reaction path calculations, based on quantitative fluid inclusion data and constrained by field observations, were used to evaluate possible precipitation mechanisms. The most important precipitation mechanism was probably the mixing of fluids containing different metal and reduced sulfur contents. Cooling, dilution, and changes in pH of the ore fluid probably played a minor role in the precipitation of ores. The optimum results that produced the most metal sulfide deposition with the least amount of fluid was the mixing of a fluid containing low amounts of reduced sulfur with a sulfur-rich, metal poor fluid. In this scenario, large amounts of sphalerite and galena are precipitated, together with smaller quantities of pyrite precipitated and dolomite dissolved. The relative amounts of metal precipitated and dolomite dissolved in this scenario agree with field observations that show only minor dolomite dissolution during ore deposition. The modeling results demonstrate the important control of the reduced sulfur concentration on the Zn and Pb transport capacity of the ore fluid and the volumes of fluid required to form the deposit. The studies of the Trèves ores provide insights into the ore-forming processes of a typical MVT deposit in the Cévennes region. However, the extent to which these processes can be extrapolated to other MVT deposits in the Cévennes region is problematic. Nevertheless, the evidence for the extensive migration of fluids in the basement and sedimentary cover rocks in the Cévennes region suggests that the ore forming processes for the Trèves deposit must be considered equally viable possibilities for the numerous fault-controlled and mineralogically similar MVT deposits in the Cévennes region.