scholarly journals Probabilistic nucleation governs time, amount, and location of mineral precipitation and geometry evolution in the porous medium

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Nooraiepour ◽  
Mohammad Masoudi ◽  
Helge Hellevang
Keyword(s):  
Porous Medium ◽  
Reactive Transport ◽  
Solid Phase ◽  
Mutual Effect ◽  
Transport Processes ◽  
Primary Control ◽  
Spatiotemporal Evolution ◽  
Mineral Precipitation ◽  
Phase Accumulation ◽  
Insight Into

AbstractOne important unresolved question in reactive transport is how pore-scale processes can be upscaled and how predictions can be made on the mutual effect of chemical processes and fluid flow in the porous medium. It is paramount to predict the location of mineral precipitation besides their amount for understanding the fate of transport properties. However, current models and simulation approaches fail to predict precisely where crystals will nucleate and grow in the spatiotemporal domain. We present a new mathematical model for probabilistic mineral nucleation and precipitation. A Lattice Boltzmann implementation of the two-dimensional mineral surface was developed to evaluate geometry evolution when probabilistic nucleation criterion is incorporated. To provide high-resolution surface information on mineral precipitation, growth, and distribution, we conducted a total of 27 calcium carbonate synthesis experiments in the laboratory. The results indicate that nucleation events as precursors determine the location and timing of crystal precipitation. It is shown that reaction rate has primary control over covering the substrate with nuclei and, subsequently, solid-phase accumulation. The work provides insight into the spatiotemporal evolution of porous media by suggesting probabilistic and deterministic domains for studying reactive transport processes. We indicate in which length- and time-scales it is essential to incorporate probabilistic nucleation for valid predictions.

Reactive Geochemical Flow Modeling With CT Scanned Rock Fractures

2014 ◽  
Author(s):  
Dustin Crandall ◽  
Hang Wen ◽  
Li Li ◽  
Alexandra Hakala
Keyword(s):  
Reactive Transport ◽  
Preferential Flow ◽  
Solid Phase ◽  
Three Dimensional ◽  
Transport Processes ◽  
Mineral Dissolution ◽  
Rock Matrix ◽  
Void Space ◽  
Reconstruction Procedure ◽  
Aperture Distribution

Obtaining quality three-dimensional geometries of fractures in a natural medium, such as rock, is a non-trivial task. This paper describes how several geothermal fractured rocks were scanned using computed tomography (CT), the reconstruction procedure to generate the three-dimensional (3D) geometry of the fractured rock, and the methodology for isolating the fracture from the CT scan. A conversion process to capture the relevant geometric features of the fracture is then discussed. The scanned aperture distribution was then used to simulate the reactive flow and transport processes using a reactive transport code CrunchFlow. The accurate use of CT images in fluid flow models within complex structures allows detailed understanding on how the aperture distribution affects mineral dissolution and fracture property evolution during the EGS process. Our preliminary simulation results show the formation of the preferential flow in zones with larger apertures, which led to higher calcite dissolution rates and even larger aperture size over time in these zones. Because calcite only occupied 10% of the solid phase, its dissolution did not completely open up the aperture because other relatively non-reactive minerals (clay and quartz) remained. The traditional measure of mechanical aperture could not take into account the partial increase in void space in the rock matrix and underestimated the increase in average aperture. The chemical and hydraulic apertures, which explicitly take into account changes in mineral volumes in the rock matrix, relate better to the overall change in the effective permeability of the sample.

scholarly journals Mechanisms for mechanical trapping of geologically sequestered carbon dioxide

2015 ◽  
Vol 471 (2175) ◽  
pp. 20140853 ◽  
Author(s):  
Yossi Cohen ◽  
Daniel H. Rothman
Keyword(s):  
Carbon Dioxide ◽  
Porous Medium ◽  
Time Evolution ◽  
Reactive Transport ◽  
Original Form ◽  
Mineral Precipitation ◽  
Rich Region ◽  
Low Concentration ◽  
Long Time ◽  
Carbonate Species

Carbon dioxide (CO 2 ) sequestration in subsurface reservoirs is important for limiting atmospheric CO 2 concentrations. However, a complete physical picture able to predict the structure developing within the porous medium is lacking. We investigate theoretically reactive transport in the long-time evolution of carbon in the brine–rock environment. As CO 2 is injected into a brine–rock environment, a carbonate-rich region is created amid brine. Within the carbonate-rich region minerals dissolve and migrate from regions of high-to-low concentration, along with other dissolved carbonate species. This causes mineral precipitation at the interface between the two regions. We argue that precipitation in a small layer reduces diffusivity, and eventually causes mechanical trapping of the CO 2 . Consequently, only a small fraction of the CO 2 is converted to solid mineral; the remainder either dissolves in water or is trapped in its original form. We also study the case of a pure CO 2 bubble surrounded by brine and suggest a mechanism that may lead to a carbonate-encrusted bubble owing to structural diffusion.

scholarly journals Transport in tight material enlightened by process tomography

2021 ◽  
Vol 1 ◽  
pp. 293-294
Author(s):  
Johannes Kulenkampff ◽  
Till Bollermann ◽  
Maria A. Cardenas Rivera ◽  
Cornelius Fischer
Keyword(s):  
Reactive Transport ◽  
Fluid Transport ◽  
Fluid Pressure ◽  
Transport Processes ◽  
Opalinus Clay ◽  
Scale Model ◽  
Transport Modelling ◽  
Barrier Materials ◽  
Process Tomography ◽  
Insight Into

Abstract. The analysis of fluid transport through tight barrier materials poses two major challenges: (i) Long equilibration periods require long minimum experiment durations, and (ii) the fluid transport frequently results in complex pattern formation. Measuring times that are too short may feign transport rates that are too low; intact homogeneous samples are often missing problematic features, e.g. fractures. Both issues are detected and analyzed by using process tomography techniques, thereby providing an improved understanding of transport processes in complex materials. We thus continuously develop and apply the positron emission tomography (PET) method for geomaterials (Kulenkampff et al., 2016). This is able to trace very low concentrations of β+-emitting radionuclides during their passage through drill cores of barrier material with reasonable resolution (1 mm) and over variable periods (hours to years). The method yields time-resolved quantitative tomographic images of the tracer concentration (e.g. https://doi.org/10.5281/zenodo.166509), in contrast to input-output experiments like common permeability measurements, diffusion cells or break-through curves. Our current research includes the analysis of diffusive transport in heterogeneous shales (sandy facies of the Opalinus Clay) (BMBF and HGF iCross project), the reactive flow in fracture-filling materials of crystalline rocks (Eurad FUTURE project) and transport in engineered barriers and the contact zone (Euratom Cebama, Eurad Magic, as well as MgO and Stroefun BMWi projects). The efforts combine flow field tomography, structural imaging and reactive transport modelling to improve process understanding and to provide a bridge from the molecular to the macroscopic scale. The benefits include: Insight into temporal stability and spatial heterogeneity of the observed transport process Parameterization of local velocity distribution and effective volume as well as comparability with pore-scale model simulations Ability to quantify multiple internal transport rates without the need to register the delayed output signal Transparent and palpable visualization of processes hidden in the opaque material The method requires specific constraints of the experimental setup (size, fluid pressure, temperature). Nevertheless, it provides unique insight into reactive transport processes observed in potential materials for nuclear waste management.

scholarly journals A “lab-on-a-chip” experiment for assessing mineral precipitation processes in fractured porous media

2020 ◽  
Author(s):  
Jenna Poonoosamy ◽  
Sophie Roman ◽  
Cyprien Soulaine ◽  
Hang Deng ◽  
Sergi Molins ◽  
...  
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Reactive Transport ◽  
Surface Passivation ◽  
Pore Scale ◽  
Mineral Precipitation ◽  
Transport Models ◽  
Mineral Transformation ◽  
Fractured Porous Medium ◽  
Fractured Medium

<p>The understanding of dissolution and precipitation of minerals and its impact on the transport of fluids in fractured media is essential for various subsurface applications including shale gas production using hydraulic fracturing (“fracking”), CO<sub>2</sub> sequestration, or geothermal energy extraction. The implementation of such coupled processes into numerical reactive transport codes requires a mechanistic process understanding and model validation with quantitative experiments. In this context, we developed a microfluidic “lab-on-chip” of a reactive fractured porous medium of 800 µm × 900 µm size with 10 µm depth. The fractured medium consisted of compacted celestine grains (grain size 4 – 9 µm). A BaCl<sub>2</sub> solution was injected into the microreactor at a flow rate of 500 nl min<sup>-1</sup>, leading to the dissolution of celestine and an epitaxial growth of barite on its surface (Poonoosamy et al., 2016). Our investigations including confocal Raman spectroscopic techniques allowed for monitoring the temporal mineral transformation at the pore scale in 2D and 3D geometries. The fractured porous medium causes a heterogeneous flow field in the microreactor that leads to spatially different mineral transformation rates. In these experiments, the dynamic evolution of surface passivation processes depends on two intertwined processes: i) the dissolution of the primary mineral that is needed for the subsequent precipitation, and ii) the suppression of the dissolution reaction as a result of secondary mineral precipitation. However, the description of evolving reactive surface areas to account for mineral passivation mechanisms in reactive transport models following Daval et al. (2009) showed several limitations, and prompt for an improved description of passivation processes that includes the diffusive properties of secondary phases (Poonoosamy et al., 2020). The results of the ongoing microfluidic experiments in combination with advanced pore-scale modelling will provide new insights regarding application and extension of the description of surface passivation processes to be included in (continuum-scale) reactive transport models.</p><p>Daval D., Martinez I., Corvisier J., Findling N., Goffé B. and Guyotac F. (2009) Carbonation of Ca-bearing silicates, the case of wollastonite: Experimental investigations and kinetic modelling. Chem. Geol. 265(1–2), 63-78.</p><p>Poonoosamy J., Curti E., Kosakowski G., Van Loon L. R., Grolimund D. and Mäder U. (2016) Barite precipitation following celestite dissolution in a porous medium: a SEM/BSE and micro XRF/XRD study. Geochim. Cosmochim. Acta 182, 131-144.</p><p>Poonoosamy J., Klinkenberg M., Deissmann G., Brandt F., Bosbach D., Mäder U. and Kosakowski G. (2020) Effects of solution supersaturation on barite precipitation in porous media and consequences on permeability: experiments and modelling. Geochim. Cosmochim. Acta 270, 43-60.</p>

Evaluation of secondary mineral precipitation by reactive transport modeling at the Ketzin CO2 storage site, Germany

2020 ◽  
Author(s):  
Eunseon Jang ◽  
Bernd Wiese ◽  
Thomas Kalbacher ◽  
Renchao Lu ◽  
Cornelia Schmidt-Hattenberger
Keyword(s):  
Reactive Transport ◽  
Transport Processes ◽  
Transport Modeling ◽  
Reactive Transport Modeling ◽  
Storage Site ◽  
Pilot Site ◽  
Secondary Mineral ◽  
Mineral Precipitation ◽  
Secondary Minerals ◽  
Gypsum Precipitation

<p>One of the major keys to the success of the carbon capture and storage (CCS) is understanding the geochemical effects that CO<sub>2</sub> has on the storage reservoir. The injection of CO<sub>2</sub> into the reservoir disturbs geochemical equilibrium as it induces acid-generation reactions with subsequent CO<sub>2</sub>-brine-mineral interactions, including dissolution of certain host minerals and precipitation of secondary minerals. The mineral precipitation, especially precipitation of carbon-bearing minerals in geological formations, is generally a favorable for CO<sub>2</sub> trapping mechanism that ensures long-term geologic CO<sub>2</sub> sequestration. These precipitates, however, may clog the wellbore and its surroundings, followed by loss of injectivity.</p><p>The current study is dedicated towards a better understanding of the geochemistry of the geological CO<sub>2</sub> storage based on the Ketzin CO<sub>2</sub> pilot site. The Ketzin CO<sub>2</sub> storage site, the first on-shore geological CO<sub>2</sub> storage site in the European mainland, is demonstrated a safe and reliable CO<sub>2</sub> storage operation after injection of about 67-kilo tons of CO<sub>2</sub> and offers the unique opportunity to work on data sets from all storage life-cycle (Martens et al., 2014). Through both field measurement and modeling studies, this contribution aims to explore the secondary mineral precipitation mechanisms and identify the major influential factors during the CO<sub>2</sub> sequestration. This approach supports the H2020 project SECURe establishing best practice in baseline investigations for subsurface geoenergy operations, underpinned by data of pilot and research-scale sites in Europe and internationally. The secondary minerals solubility was investigated as a function of the reservoir temperature, pressure, and CO<sub>2</sub> concentration, which occurred in the reservoir. Special focus is set to sulfate minerals, as field evidence exists that gypsum precipitates as a result of reservoir exposition to CO<sub>2</sub>. Batch modeling was performed using the PHREEQC code version 3 (Parkhurst and Appelo, 2013) with the Pitzer database (pitzer.dat). The coupling interface OGS#IPhreeqc (He et al., 2015) applied reactive transport modeling, and the coupled reactive-transport processes in the reservoir with complex chemistry can be modeled. Our results suggest that the gypsum precipitation was found to increase as CO<sub>2</sub> concentration ascends. However, no significant porosity and permeability alterations are observed since the gypsum precipitation acts as a Ca<sup>2+</sup> sink and leads to further carbonate dissolution. The results highlight the high reactivity of the near-well zone due to CO<sub>2</sub> injection and emphasize the need to be monitored in the injection well to avoid the potential formation of gypsum, which could lead to well clogging.</p><p>He, W., Beyer, C., Fleckenstein, J.H., Jang, E., Kolditz, O., Naumov, D., Kalbacher, T., 2015. A parallelization scheme to simulate reactive transport in the subsurface environment with OGS#IPhreeqc 5.5.7-3.1.2. Geosci. Model Dev. 8, 3333-3348.</p><p>Martens, S., Möller, F., Streibel, M., Liebscher, A., 2014. Completion of Five Years of Safe CO2 Injection and Transition to the Post-closure Phase at the Ketzin Pilot Site. Energy Procedia 59, 190-197.</p><p>Parkhurst, D.L., Appelo, C.A.J., 2013. Description of input and examples for PHREEQC version 3: a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations, Techniques and Methods, Reston, Virginia, USA, p. 519.</p>

Modelling uranium leaching from agricultural soils to groundwater as a criterion for comparison with complementary safety indicators

2006 ◽  
Vol 932 ◽  
Author(s):  
D. Jacques ◽  
J. Šimůnek ◽  
D. Mallants ◽  
M.Th. van Genuchten
Keyword(s):  
Soil Profile ◽  
Reactive Transport ◽  
Transport Model ◽  
Agricultural Soils ◽  
Solid Phase ◽  
Water Flux ◽  
Fertilizer Application ◽  
Mineral Fertilizers ◽  
Deep Soil ◽  
Long Time

ABSTRACTNaturally occurring radionuclides can also end up in soils and groundwater due to human practices, such as application of certain fertilizers in agriculture. Many mineral fertilizers, particularly (super)phosphates, contain small amounts of 238U and 230Th which eventually may be leached from agricultural soils to underlying water resources. Field soils that receive P-fertilizers accumulate U and Th and their daughter nuclides, which eventually may leach to groundwater. Our objective was to numerically assess U migration in soils. Calculations were based on a new reactive transport model, HP1, which accounts for interactions between U and organic matter, phosphate, and carbonate. Solid phase interactions were simulated using a surface complexation module. Furthermore, all geochemical processes were coupled with a model accounting for dynamic changes in the soil water content and the water flux. The capabilities of the code in calculating natural U fluxes to groundwater were illustrated using a semi-synthetic 200-year long time series of climatological data for Belgium. Based on an average fertilizer application, the input of phosphate and uranium in the soil was defined. This paper discusses calculated U distributions in the soil profile as well as calculated U fluxes leached from a 100-cm deep soil profile. The calculated long-term leaching rates originating from fertilization are significantly higher after 200 years than estimated release rates from lowlevel nuclear waste repositories.

Porous media as a canvas for hydro-bio-geo-chemical processes: Facing the challenges

2021 ◽  
Author(s):  
Xavier Sanchez-Vila
Keyword(s):  
Porous Media ◽  
Reactive Transport ◽  
Field Work ◽  
Open Science ◽  
Transport Processes ◽  
Aquifer Recharge ◽  
Music Production ◽  
Emerging Compounds ◽  
Technological Developments ◽  
Large Research

<p>The more we study flow and transport processes in porous media, the larger the number of questions that arise. Heterogeneity, uncertainty, multidisciplinarity, and interdisciplinarity are key words that make our live as researchers miserable… and interesting. There are many ways of facing complexity; this is equivalent as deciding what colors and textures to consider when being placed in front of a fresh canvas, or what are the sounds to include and combine in a music production. You can try to get as much as you can from one discipline, using very sophisticated state-of-the-art models. On the other hand, you can choose to bring to any given problem a number of disciplines, maybe having to sacrifice deepness in exchange of the better good of yet still sophisticated multifaceted solutions. There are quite a number of examples of the latter approach. In this talk, I will present a few of those, eventually concentrating in managed aquifer recharge (MAR) practices. This technology involves water resources from a myriad of perspectives, covering from climate change to legislation, from social awareness to reactive transport, from toxicological issues to biofilm formation, from circular economy to emerging compounds, from research to pure technological developments, and more. All of these elements deserve our attention as researchers, and we cannot pretend to master all of them. Integration, development of large research groups, open science are words that will appear in this talk. So does mathematics, and physics, and geochemistry, and organic chemistry, and biology. In any given hydrogeological problem you might need to combine equations, statistics, experiments, field work, and modeling; expect all of them in this talk. As groundwater complexity keeps amazing and mesmerizing me, do not expect solutions being provided, just anticipate more and more challenging research questions being asked.</p>

Assessment of groundwater contamination by chlorpyrifos using the PWC model in Valencia Region (Spain)

2021 ◽  
Author(s):  
Ricardo Pérez Indoval ◽  
Javier Rodrigo-Ilarri ◽  
Eduardo Cassiraga
Keyword(s):  
Reactive Transport ◽  
Management Practices ◽  
Fate And Transport ◽  
Environmental Modeling ◽  
Transport Processes ◽  
Negative Effects ◽  
Advection Dispersion ◽  
Agricultural Applications ◽  
Transformation Processes ◽  
Mass Transport Equation

<p>Chlorpyrifos is commoly used as an pesticide to control weeds and prevent nondesirable grow of algae, fungi and bacteria in many agricultural applications. Despite its highly negative effects on human health, environmental modeling of this kind of pesticide in the groundwater is not commonly done in real situations. Predicting the fate of pesticides released into the natural environment is necessary to anticipate and minimize adverse effects both at close and long distances from the contamination source. A number of models have been developed to predict the behavior, mobility, and persistence of pesticides. These models should account for key hydrological and agricultural processes, such as crop growth, pesticide application patterns, transformation processes and field management practices.</p><p>This work shows results obtained by the Pesticide Water Calculator (PWC) model to simulate the behavior of chlorpyrifos. PWC model is used as a standard pesticide simulation model in USA and in this work it has been used to  simulate the fate and transport of chlorpyrifos in the unsaturated zone of the aquifer. The model uses a whole set of parameters to solve a modified version of the mass transport equation considering the combined effect of advection, dispersion and reactive transport processes. PWC is used to estimate the daily concentrations of chlorpyrifos in the Buñol-Cheste aquifer in Valencia Region(Spain).</p><p>A whole set of simulation scenarios have been designed to perform a parameter sensitivity analysis. Results of the PWC model obtained in this study represents a crucial first step towards the development of a pesticide risk assessment in Valencia Region. Results show that numerical simulation is a valid tool for the analysis and prediction of the fate  and transport of pesticides in the groundwater.</p>

scholarly journals Pore-Scale Modeling of Mineral Growth and Nucleation in Reactive Flow

2022 ◽  
Vol 3 ◽  
Author(s):  
Vitalii Starchenko
Keyword(s):  
Reactive Transport ◽  
Surface Reaction ◽  
Nucleation Theory ◽  
Crystal Nucleation ◽  
Classical Nucleation Theory ◽  
Reactive Flow ◽  
Natural Environments ◽  
Pore Scale ◽  
Arbitrary Lagrangian Eulerian ◽  
Mineral Precipitation

A fundamental understanding of mineral precipitation kinetics relies largely on microscopic observations of the dynamics of mineral surfaces exposed to supersaturated solutions. Deconvolution of tightly bound transport, surface reaction, and crystal nucleation phenomena still remains one of the main challenges. Particularly, the influence of these processes on texture and morphology of mineral precipitate remains unclear. This study presents a coupling of pore-scale reactive transport modeling with the Arbitrary Lagrangian-Eulerian approach for tracking evolution of explicit solid interface during mineral precipitation. It incorporates a heterogeneous nucleation mechanism according to Classical Nucleation Theory which can be turned “on” or “off.” This approach allows us to demonstrate the role of nucleation on precipitate texture with a focus at micrometer scale. In this work precipitate formation is modeled on a 10 micrometer radius particle in reactive flow. The evolution of explicit interface accounts for the surface curvature which is crucial at this scale in the regime of emerging instabilities. The results illustrate how the surface reaction and reactive fluid flow affect the shape of precipitate on a solid particle. It is shown that nucleation promotes the formation of irregularly shaped precipitate and diminishes the effect of the flow on the asymmetry of precipitation around the particle. The observed differences in precipitate structure are expected to be an important benchmark for reaction-driven precipitation in natural environments.

Natural Convection Inside a Bidisperse Porous Medium Enclosure

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Arunn Narasimhan ◽  
B. V. K. Reddy
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Volume Fraction ◽  
Solid Phase ◽  
Darcy Number ◽  
The Core ◽  
Side Walls ◽  
Porous Blocks ◽  
Rayleigh Numbers

Bidisperse porous medium (BDPM) consists of a macroporous medium whose solid phase is replaced with a microporous medium. This study investigates using numerical simulations, steady natural convection inside a square BDPM enclosure made from uniformly spaced, disconnected square porous blocks that form the microporous medium. The side walls are subjected to differential heating, while the top and bottom ones are kept adiabatic. The bidispersion effect is generated by varying the number of blocks (N2), macropore volume fraction (ϕE), and internal Darcy number (DaI) for several enclosure Rayleigh numbers (Ra). Their effect on the BDPM heat transfer (Nu) is investigated. When Ra is fixed, the Nu increases with an increase in both DaI and DaE. At low Ra values, Nu is strongly affected by both DaI and ϕE. When N2 is fixed, at high Ra values, the porous blocks in the core region have negligible effect on the Nu. A correlation is proposed to evaluate the heat transfer from the BDPM enclosure, Nu, as a function of Raϕ, DaE, DaI, and N2. It predicts the numerical results of Nu within ±15% and ±9% in two successive ranges of modified Rayleigh number, RaϕDaE.

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