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Special Issue "Modeling Multiphase Flow and Reactive Transport in Porous Media"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "G1: Petroleum Engineering".

Deadline for manuscript submissions: closed (30 March 2022) | Viewed by 9034

Special Issue Editors

Prof. Dr. Reza Soltanian
E-Mail Website
Guest Editor
Department of Geology, University of Cincinnati, Cincinnati, OH 45221-0013, USA
Interests: numerical modeling; unsaturated soil behavior; ground water flow
Special Issues, Collections and Topics in MDPI journals
Dr. Marwan Fahs
E-Mail Website
Guest Editor
National School for Water and Environmental Engineering of Strasbourg, University of Strasbourg, Strasbourg, France
Interests: fluid mechanics; heat and mass transfer; porous media
Prof. Dr. Hussein Hoteit
E-Mail Website
Guest Editor
Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
Interests: reservoir simulation; modeling fractured reservoirs; enhanced oil recovery; flow and transport
Special Issues, Collections and Topics in MDPI journals
Prof. Zhenxue Dai
E-Mail Website
Guest Editor
College of Construction Engineering, Jilin University, Changchun, China
Interests: geochemical modeling; flow and transport in porous media; carbon storage; reservoir characterization; nuclear waste disposal
Prof. Dr. Jesús Carrera
E-Mail Website
Guest Editor
Department of Geosciences, Spanish National Research Council (CSIC), Barcelona, Spain
Interests: groundwater; CO2 storage; reactive transport; managed aquifer recharge; seawater intrusion

Special Issue Information

Dear Colleagues,

This Special Issue focuses on recent advances and developments in the modeling of multiphase flow and reactive transport in porous media. Many fundamental and practical aspects of multiphase flow processes, which are crucial in various energy and environmental applications, are not well understood. For instance, how are the processes controlled by interplay between large-scale flow patterns, such as fingering and local-scale Fickian diffusion, mechanical dispersion, and chemical reaction? How can we incorporate small-scale physical and chemical processes in the pore and core-scale into large-scale multiphase flow and transport models? How does the heterogeneous nature of rock–fluid properties and its uncertainty impact multiphase flow dynamics? What are the implications of thermodynamic changes in fluid properties?

Our goal is to include comprehensive review papers and recent experimental, theoretical, and numerical results, related to the study of complexities in describing multiphase flow dynamics and transport in porous media across a wide range of spatial and temporal scales, including uncertainty analysis and risk assessment of operations. In particular, topics of interest include but are not limited to:

  • Multiphase flow in porous and fractured reservoirs;
  • Geochemistry and reactive transport;
  • Pore-scale processes;
  • Constitutive relations;
  • Enhanced oil/gas recovery;
  • Upscaling flow and transport parameters;
  • Coupled hydraulic, thermal, mechanical, chemical, and biological processes;
  • Advanced modeling framework and methods.

Dr. Reza Soltanian
Dr. Marwan Fahs
Dr. Hussein Hoteit
Dr. Zhenxue Dai
Dr. Jesús Carrera
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • multiphase flow
  • porous media
  • reactive transport
  • pore scale
  • continuum scale

Published Papers (13 papers)

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Research

Jump to: Review

Article
Effects of Diffusion, Adsorption, and Hysteresis on Huff-n-Puff Performance in Ultratight Reservoirs with Different Fluid Types and Injection Gases
Energies 2021, 14(21), 7379; https://doi.org/10.3390/en14217379 - 05 Nov 2021
Viewed by 424
Abstract
Cyclic solvent injection, known as solvent huff-n-puff, is one of the promising techniques for enhancing oil recovery from shale reservoirs. This study investigates the huff-n-puff performance in ultratight shale reservoirs by conducting large-scale numerical simulations for a wide range of reservoir fluid types [...] Read more.
Cyclic solvent injection, known as solvent huff-n-puff, is one of the promising techniques for enhancing oil recovery from shale reservoirs. This study investigates the huff-n-puff performance in ultratight shale reservoirs by conducting large-scale numerical simulations for a wide range of reservoir fluid types (retrograde condensate, volatile oil, and black oil) and different injection gases (CO2, C2H6, and C3H8). A dual-porosity compositional model is utilized to comprehensively evaluate the impact of multicomponent diffusion, adsorption, and hysteresis on the production performance of each reservoir fluid and the retention capacity of the injection gases. The results show that the huff-n-puff process improves oil recovery by 4–6% when injected with 10% PV of gas. Huff-n-puff efficiency increases with decreasing gas-oil ratio (GOR). C2H6 provides the highest recovery for the black oil and volatile oil systems, and CO2 provides the highest recovery for retrograde condensate fluid type. Diffusion and adsorption are essential mechanisms to be considered when modeling gas injection in shale reservoirs. However, the relative permeability hysteresis effect is not significant. Diffusion impact increases with GOR, while adsorption impact decreases with increasing GOR. Oil density reduction caused by diffusion is observed more during the soaking period considering that the diffusion of the injected gas caused a low prediction error, while adsorption for the injected gas showed a noticeable error. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
The Multi-Advective Water Mixing Approach for Transport through Heterogeneous Media
Energies 2021, 14(20), 6562; https://doi.org/10.3390/en14206562 - 12 Oct 2021
Cited by 2 | Viewed by 537
Abstract
Finding a numerical method to model solute transport in porous media with high heterogeneity is crucial, especially when chemical reactions are involved. The phase space formulation termed the multi-advective water mixing approach (MAWMA) was proposed to address this issue. The water parcel method [...] Read more.
Finding a numerical method to model solute transport in porous media with high heterogeneity is crucial, especially when chemical reactions are involved. The phase space formulation termed the multi-advective water mixing approach (MAWMA) was proposed to address this issue. The water parcel method (WP) may be obtained by discretizing MAWMA in space, time, and velocity. WP needs two transition matrices of velocity to reproduce advection (Markovian in space) and mixing (Markovian in time), separately. The matrices express the transition probability of water instead of individual solute concentration. This entails a change in concept, since the entire transport phenomenon is defined by the water phase. Concentration is reduced to a chemical attribute. The water transition matrix is obtained and is demonstrated to be constant in time. Moreover, the WP method is compared with the classic random walk method (RW) in a high heterogeneous domain. Results show that the WP adequately reproduces advection and dispersion, but overestimates mixing because mixing is a sub-velocity phase process. The WP method must, therefore, be extended to take into account incomplete mixing within velocity classes. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
A Generalized Finite Volume Method for Density Driven Flows in Porous Media
Energies 2021, 14(19), 6151; https://doi.org/10.3390/en14196151 - 27 Sep 2021
Viewed by 485
Abstract
In this article, we consider a time evolution equation for solute transport, coupled with a pressure equation in space dimension 2. For the numerical discretization, we combine the generalized finite volume method SUSHI on adaptive meshes with a time semi-implicit scheme. In the [...] Read more.
In this article, we consider a time evolution equation for solute transport, coupled with a pressure equation in space dimension 2. For the numerical discretization, we combine the generalized finite volume method SUSHI on adaptive meshes with a time semi-implicit scheme. In the first part of this article, we present numerical simulations for two problems: a rotating interface between fresh and salt water and a well-known test case proposed by Henry. In the second part, we also introduce heat transfer and perform simulations for a system from the documentation of the software SEAWAT. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Discovery of Dynamic Two-Phase Flow in Porous Media Using Two-Dimensional Multiphase Lattice Boltzmann Simulation
Energies 2021, 14(13), 4044; https://doi.org/10.3390/en14134044 - 05 Jul 2021
Cited by 5 | Viewed by 886
Abstract
The dynamic two-phase flow in porous media was theoretically developed based on mass, momentum conservation, and fundamental constitutive relationships for simulating immiscible fluid-fluid retention behavior and seepage in the natural geomaterial. The simulation of transient two-phase flow seepage is, therefore, dependent on both [...] Read more.
The dynamic two-phase flow in porous media was theoretically developed based on mass, momentum conservation, and fundamental constitutive relationships for simulating immiscible fluid-fluid retention behavior and seepage in the natural geomaterial. The simulation of transient two-phase flow seepage is, therefore, dependent on both the hydraulic boundaries applied and the immiscible fluid-fluid retention behavior experimentally measured. Many previous studies manifested the velocity-dependent capillary pressure–saturation relationship (Pc-S) and relative permeability (Kr-S). However, those works were experimentally conducted on a continuum scale. To discover the dynamic effects from the microscale, the Computational Fluid Dynamic (CFD) is usually adopted as a novel method. Compared to the conventional CFD methods solving Naiver–Stokes (NS) equations incorporated with the fluid phase separation schemes, the two-phase Lattice Boltzmann Method (LBM) can generate the immiscible fluid-fluid interface using the fluid-fluid/solid interactions at a microscale. Therefore, the Shan–Chen multiphase multicomponent LBM was conducted in this study to simulate the transient two-phase flow in porous media. The simulation outputs demonstrate a preferential flow path in porous media after the non-wetting phase fluid is injected until, finally, the void space is fully occupied by the non-wetting phase fluid. In addition, the inter-relationships for each pair of continuum state variables for a Representative Elementary Volume (REV) of porous media were analyzed for further exploring the dynamic nonequilibrium effects. On one hand, the simulating outcomes reconfirmed previous findings that the dynamic effects are dependent on both the transient seepage velocity and interfacial area dynamics. Nevertheless, in comparison to many previous experimental studies showing the various distances between the parallelly dynamic and static Pc-S relationships by applying various constant flux boundary conditions, this study is the first contribution showing the Pc-S striking into the nonequilibrium condition to yield dynamic nonequilibrium effects and finally returning to the equilibrium static Pc-S by applying various pressure boundary conditions. On the other hand, the flow regimes and relative permeability were discussed with this simulating results in regards to the appropriateness of neglecting inertial effects (both accelerating and convective) in multiphase hydrodynamics for a highly pervious porous media. Based on those research findings, the two-phase LBM can be demonstrated to be a powerful tool for investigating dynamic nonequilibrium effects for transient multiphase flow in porous media from the microscale to the REV scale. Finally, future investigations were proposed with discussions on the limitations of this numerical modeling method. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Improved IMPES Scheme for the Simulation of Incompressible Three-Phase Flows in Subsurface Porous Media
Energies 2021, 14(10), 2757; https://doi.org/10.3390/en14102757 - 11 May 2021
Cited by 1 | Viewed by 549
Abstract
In this work, an improved IMplicit Pressure and Explicit Saturation (IMPES) scheme is proposed to solve the coupled partial differential equations to simulate the three-phase flows in subsurface porous media. This scheme is the first IMPES algorithm for the three-phase flow problem that [...] Read more.
In this work, an improved IMplicit Pressure and Explicit Saturation (IMPES) scheme is proposed to solve the coupled partial differential equations to simulate the three-phase flows in subsurface porous media. This scheme is the first IMPES algorithm for the three-phase flow problem that is locally mass conservative for all phases. The key technique of this novel scheme relies on a new formulation of the discrete pressure equation. Different from the conventional scheme, the discrete pressure equation in this work is obtained by adding together the discrete conservation equations of all phases, thus ensuring the consistency of the pressure equation with the three saturation equations at the discrete level. This consistency is important, but unfortunately it is not satisfied in the conventional IMPES schemes. In this paper, we address and fix an undesired and well-known consequence of this inconsistency in the conventional IMPES in that the computed saturations are conservative only for two phases in three-phase flows, but not for all three phases. Compared with the standard IMPES scheme, the improved IMPES scheme has the following advantages: firstly, the mass conservation of all the phases is preserved both locally and globally; secondly, it is unbiased toward all phases, i.e., no reference phases need to be chosen; thirdly, the upwind scheme is applied to the saturation of all phases instead of only the referenced phases; fourthly, numerical stability is greatly improved because of phase-wise conservation and unbiased treatment. Numerical experiments are also carried out to demonstrate the strength of the improved IMPES scheme. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Semi-Analytical Solution to Assess CO2 Leakage in the Subsurface through Abandoned Wells
Energies 2021, 14(9), 2452; https://doi.org/10.3390/en14092452 - 25 Apr 2021
Cited by 5 | Viewed by 649
Abstract
Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of [...] Read more.
Geological carbon storage is an effective method capable of reducing carbon dioxide (CO2) emissions at significant scales. Subsurface reservoirs with sealing caprocks can provide long-term containment for the injected fluid. Nevertheless, CO2 leakage is a major concern. The presence of abandoned wells penetrating the reservoir caprock may cause leakage flow-paths for CO2 to the overburden. Assessment of time-varying leaky wells is a need. In this paper, we propose a new semi-analytical approach based on pressure-transient analysis to model the behavior of CO2 leakage and corresponding pressure distribution within the storage site and the overburden. Current methods assume instantaneous leakage of CO2 occurring with injection, which is not realistic. In this work, we employ the superposition in time and space to solve the diffusivity equation in 2D radial flow to approximate the transient pressure in the reservoirs. Fluid and rock compressibilities are taken into consideration, which allow calculating the breakthrough time and the leakage rate of CO2 to the overburden accurately. We use numerical simulations to verify the proposed time-dependent semi-analytical solution. The results show good agreement in both pressure and leakage rates. Sensitivity analysis is then conducted to assess different CO2 leakage scenarios to the overburden. The developed semi-analytical solution provides a new simple and practical approach to assess the potential of CO2 leakage outside the storage site. This approach is an alternative to numerical methods when detailed simulations are not feasible. Furthermore, the proposed solution can also be used to verify numerical codes, which often exhibit numerical artifacts. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Pore-Scale Simulation of Particle Flooding for Enhancing Oil Recovery
Energies 2021, 14(8), 2305; https://doi.org/10.3390/en14082305 - 19 Apr 2021
Cited by 2 | Viewed by 590
Abstract
The particles, water and oil three-phase flow behaviors at the pore scale is significant to clarify the dynamic mechanism in the particle flooding process. In this work, a newly developed direct numerical simulation techniques, i.e., VOF-FDM-DEM method is employed to perform the simulation [...] Read more.
The particles, water and oil three-phase flow behaviors at the pore scale is significant to clarify the dynamic mechanism in the particle flooding process. In this work, a newly developed direct numerical simulation techniques, i.e., VOF-FDM-DEM method is employed to perform the simulation of several different particle flooding processes after water flooding, which are carried out with a porous structure obtained by CT scanning of a real rock. The study on the distribution of remaining oil and the displacement process of viscoelastic particles shows that the capillary barrier near the location with the abrupt change of pore radius is the main reason for the formation of remaining oil. There is a dynamic threshold in the process of producing remaining oil. Only when the displacement force exceeds this threshold, the remaining oil can be produced. The flow behavior of particle–oil–water under three different flooding modes, i.e., continuous injection, alternate injection and slug injection, is studied. It is found that the particle size and the injection mode have an important influence on the fluid flow. On this basis, the flow behavior, pressure characteristics and recovery efficiency of the three injection modes are compared. It is found that by injecting two kinds of fluids with different resistance increasing ability into the pores, they can enter into different pore channels, resulting in the imbalance of the force on the remaining oil interface and formation of different resistance between the channels, which can realize the rapid recovery of the remaining oil. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Quantifying the Low Salinity Waterflooding Effect
Energies 2021, 14(7), 1979; https://doi.org/10.3390/en14071979 - 02 Apr 2021
Cited by 1 | Viewed by 535
Abstract
Low salinity waterflooding (LSW) has shown promising results in terms of increasing oil recovery at laboratory scale. In this work, we study the LSW effect, at laboratory scale, and provide a basis for quantifying the effect at field scale by extracting reliable relative [...] Read more.
Low salinity waterflooding (LSW) has shown promising results in terms of increasing oil recovery at laboratory scale. In this work, we study the LSW effect, at laboratory scale, and provide a basis for quantifying the effect at field scale by extracting reliable relative permeability curves. These were achieved by experimental and numerical interpretation of laboratory core studies. Carbonate rock samples were used to conduct secondary and tertiary unsteady-state coreflooding experiments at reservoir conditions. A mathematical model was developed as a research tool to interpret and further validate the physical plausibility of the coreflooding experiments. At core scale and a typical field rate of ~1 ft/day, low salinity water (LS) resulted in not only ~20% higher oil recovery compared to formation water (FW) but also recovered oil sooner. LS water also showed capability of reducing the residual oil saturation when flooded in tertiary mode. The greater oil recovery caused by LSW can be attributed to altering the wettability of the rock to less oil-wet as confirmed by the numerically extracted relative permeability curves. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Quantitative Analysis and Evaluation of Coal Mine Geological Structures Based on Fractal Theory
Energies 2021, 14(7), 1925; https://doi.org/10.3390/en14071925 - 31 Mar 2021
Viewed by 510
Abstract
With the increasing depth of coal mining, the quantitative evaluation of the degree of geological structure development is becoming increasingly important for the control of mine water hazards in coal mining areas. Understanding the complexity of geological structure development can improve the safety [...] Read more.
With the increasing depth of coal mining, the quantitative evaluation of the degree of geological structure development is becoming increasingly important for the control of mine water hazards in coal mining areas. Understanding the complexity of geological structure development can improve the safety and efficiency of coal production. At present, various evaluation indicators of the geological structure development cannot fully reflect the complexity of faults and folds, and the evaluation process is usually affected by subjective human factors. In this paper, the fractal dimension from fractal theory is used as the evaluation indicator to quantitatively analyze and evaluate the complexity of fault and fold structure in the mining area. To verify the evaluation results, the mathematical geology method is applied in an analysis of the trend surface of fault and fold networks. The results indicate that the fractal dimension can be applied for the quantitative analysis and evaluation of the complexity of fault and fold networks. In addition, the outcome of this work provides new insights into how to characterize the fault and fold structures of coal mining areas in northern China, and has some important implications to ensure the coal production safety. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
Analysis of Crack Initiation and Propagation Thresholds of Inclined Cracks under High-Pressure Grouting in Ordovician Limestone
Energies 2021, 14(2), 360; https://doi.org/10.3390/en14020360 - 11 Jan 2021
Cited by 2 | Viewed by 669
Abstract
Control of the grouting pressure within the critical grouting pressure for crack propagation in Ordovician limestone can not only ensure grout penetration length, but also prevent the risk of creating an artificial water channel. Based on the fracture mechanics theory, a formula was [...] Read more.
Control of the grouting pressure within the critical grouting pressure for crack propagation in Ordovician limestone can not only ensure grout penetration length, but also prevent the risk of creating an artificial water channel. Based on the fracture mechanics theory, a formula was proposed to calculate the critical grouting pressure of mixed mode I-II cracks in Ordovician limestone. The necessary conditions for tilted crack opening, the rationality of the existing empirical value of the maximum allowable grouting pressure was investigated based on the mechanical model. The RFPA2D-Flow numerical simulation software was used to evaluate the deduced theory. The research results show that the deduced theoretical calculation formula of the critical grouting pressure agrees with the numerical simulation results; when the mixed mode I-II fracture initiation occurs, the grouting pressure exceeds the perpendicular stress of the overlying rock; the greater the density of the overlying rock mass, the greater the value of grouting pressure for fracture initiation; when the side pressure coefficient was ≥1, crack dip angle increased and the grouting pressure for fracture initiation tended to decrease; and the empirical grouting pressure at the maximum allowable grouting pressure is 2.0–2.5 pw, which will not cause propagation and failure of the existing crack. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
A Computational Workflow for Flow and Transport in Fractured Porous Media Based on a Hierarchical Nonlinear Discrete Fracture Modeling Approach
Energies 2020, 13(24), 6667; https://doi.org/10.3390/en13246667 - 17 Dec 2020
Cited by 2 | Viewed by 570
Abstract
Modeling flow and transport in fractured porous media has been a topic of intensive research for a number of energy- and environment-related industries. The presence of multiscale fractures makes it an extremely challenging task to resolve accurately and efficiently the flow dynamics at [...] Read more.
Modeling flow and transport in fractured porous media has been a topic of intensive research for a number of energy- and environment-related industries. The presence of multiscale fractures makes it an extremely challenging task to resolve accurately and efficiently the flow dynamics at both the local and global scales. To tackle this challenge, we developed a computational workflow that adopts a two-level hierarchical strategy based on fracture length partitioning. This was achieved by specifying a partition length to split the discrete fracture network (DFN) into small-scale fractures and large-scale fractures. Flow-based numerical upscaling was then employed to homogenize the small-scale fractures and the porous matrix into an equivalent/effective single medium, whereas the large-scale fractures were modeled explicitly. As the effective medium properties can be fully tensorial, the developed hierarchical framework constructed the discrete systems for the explicit fracture–matrix sub-domains using the nonlinear two-point flux approximation (NTPFA) scheme. This led to a significant reduction of grid orientation effects, thus developing a robust, applicable, and field-relevant framework. To assess the efficacy of the proposed hierarchical workflow, several numerical simulations were carried out to systematically analyze the effects of the homogenized explicit cutoff length scale, as well as the fracture length and orientation distributions. The effect of different boundary conditions, namely, the constant pressure drop boundary condition and the linear pressure boundary condition, for the numerical upscaling on the accuracy of the workflow was investigated. The results show that when the partition length is much larger than the characteristic length of the grid block, and when the DFN has a predominant orientation that is often the case in practical simulations, the workflow employing linear pressure boundary conditions for numerical upscaling give closer results to the full-model reference solutions. Our findings shed new light on the development of meaningful computational frameworks for highly fractured, heterogeneous geological media where fractures are present at multiple scales. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Article
PFLOTRAN-SIP: A PFLOTRAN Module for Simulating Spectral-Induced Polarization of Electrical Impedance Data
Energies 2020, 13(24), 6552; https://doi.org/10.3390/en13246552 - 11 Dec 2020
Viewed by 709
Abstract
Spectral induced polarization (SIP) is a non-intrusive geophysical method that collects chargeability information (the ability of a material to retain charge) in the time domain or its phase shift in the frequency domain. Although SIP is a temporal method, it cannot measure the [...] Read more.
Spectral induced polarization (SIP) is a non-intrusive geophysical method that collects chargeability information (the ability of a material to retain charge) in the time domain or its phase shift in the frequency domain. Although SIP is a temporal method, it cannot measure the dynamics of flow and solute/species transport in the subsurface over long times (i.e., 10–100 s of years). Data collected with the SIP technique need to be coupled with fluid flow and reactive-transport models in order to capture long-term dynamics. To address this challenge, PFLOTRAN-SIP was built to couple SIP data to fluid flow and solute transport processes. Specifically, this framework couples the subsurface flow and transport simulator PFLOTRAN and geoelectrical simulator E4D without sacrificing computational performance. PFLOTRAN solves the coupled flow and solute-transport process models in order to estimate solute concentrations, which were used in Archie’s model to compute bulk electrical conductivities at near-zero frequency. These bulk electrical conductivities were modified while using the Cole–Cole model to account for frequency dependence. Using the estimated frequency-dependent bulk conductivities, E4D simulated the real and complex electrical potential signals for selected frequencies for SIP. These frequency-dependent bulk conductivities contain information that is relevant to geochemical changes in the system. This study demonstrated that the PFLOTRAN-SIP framework is able to detect the presence of a tracer in the subsurface. SIP offers a significant benefit over ERT in the form of greater information content. It provided multiple datasets at different frequencies that better constrained the tracer distribution in the subsurface. Consequently, this framework allows for practitioners of environmental hydrogeophysics and biogeophysics to monitor the subsurface with improved resolution. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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Review

Jump to: Research

Review
Reactive Transport: A Review of Basic Concepts with Emphasis on Biochemical Processes
Energies 2022, 15(3), 925; https://doi.org/10.3390/en15030925 - 27 Jan 2022
Viewed by 768
Abstract
Reactive transport (RT) couples bio-geo-chemical reactions and transport. RT is important to understand numerous scientific questions and solve some engineering problems. RT is highly multidisciplinary, which hinders the development of a body of knowledge shared by RT modelers and developers. The goal of [...] Read more.
Reactive transport (RT) couples bio-geo-chemical reactions and transport. RT is important to understand numerous scientific questions and solve some engineering problems. RT is highly multidisciplinary, which hinders the development of a body of knowledge shared by RT modelers and developers. The goal of this paper is to review the basic conceptual issues shared by all RT problems, so as to facilitate advancement along the current frontier: biochemical reactions. To this end, we review the basic equations to indicate that chemical systems are controlled by the set of equilibrium reactions, which are easy to model, but whose rate is controlled by mixing. Since mixing is not properly represented by the standard advection-dispersion equation (ADE), we conclude that this equation is poor for RT. This leads us to review alternative transport formulations, and the methods to solve RT problems using both the ADE and alternative equations. Since equilibrium is easy, difficulties arise for kinetic reactions, which is especially true for biochemistry, where numerous challenges are open (how to represent microbial communities, impact of genomics, effect of biofilms on flow and transport, etc.). We conclude with the basic eleven conceptual issues that we consider fundamental for any conceptually sound RT effort. Full article
(This article belongs to the Special Issue Modeling Multiphase Flow and Reactive Transport in Porous Media)
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