Effects of porosity heterogeneity on chemical dissolution-front instability in fluid-saturated rocks

Zhao, Chong Bin; Schaubs, Peter; Hobbs, B. E.

doi:10.1007/s11771-017-3473-1

Cited by 10 publications

(7 citation statements)

References 18 publications

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“…The increase in porosity in the stratified model in which the mineral zones do not extend from the left to the right boundaries (scenario 4) is only 1%. This result agrees with the findings of Min et al [19] and Zhao et al [26], who reported that heterogeneities in mineral distribution can greatly affect the evolution of karst systems. In addition, the reactive transport models confirm that the dissolution of these highly soluble sulfate minerals is responsible for the excess of dissolved sulfate, sodium, and magnesium detected in the hydrogeochemical conceptual model of the Villar de Cañas area [77][78][79].…”

Section: Discussionsupporting

confidence: 93%

“…In addition, the generalized use of permeability-porosity relationships in numerical models is another source of uncertainty, since it depends on many factors, such as the structure of the rock, the mineralogy, and the dissolution processes [22]. One of the most accepted models relating porosity to permeability is the Kozeny-Carman model [23][24][25][26][27][28][29][30]. However, additional permeability-porosity relationships have been proposed recently and have been implemented in numerical codes, such as the modified Fair-Hatch model [31] and the Verma-Pruess model [32].…”

Section: Introductionmentioning

confidence: 99%

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Reactive Transport Model of Gypsum Karstification in Physically and Chemically Heterogeneous Fractured Media

et al. 2022

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Gypsum dissolution leads to the development of karstic features within much shorter timescales than in other sedimentary rocks, potentially leading to rapid deterioration of groundwater quality and increasing the risk of catastrophes caused by subsidence. Here, we present a 2-D reactive transport model to evaluate gypsum karstification in physically and chemically heterogeneous systems. The model considers a low-permeability rock matrix composed mainly of gypsum and a discontinuity (fracture), which acts as a preferential water pathway. Several scenarios are analyzed and simulated to investigate the relevance for gypsum karstification of: (1) the dynamic update of flow and transport parameters due to porosity changes; (2) the spatial distribution of minerals in the rock matrix; (3) the time evolution of water inflows through the boundaries of the model; (4) the functions relating permeability, k, to porosity, ϕ. The average porosity of the matrix after 1000 years of simulation increases from 0.045 to 0.29 when flow, transport, and chemical parameters and the water inflows through the boundary are dynamically updated according to the porosity changes. On the contrary, the porosity of the matrix hardly changes when the porosity feedback effect is not considered, while its average increases to 0.13 if the water inflow occurs through the discontinuity. Moreover, the dissolution of small amounts of highly soluble sulfate minerals plays a major role in the development of additional fractures. The increase in hydraulic conductivity is largest for the power law with an exponent of n = 5, as well as the Kozeny-Carman and the modified Fair-atch k-ϕ relationships. The gypsum dissolution front propagates into the matrix faster when the power law with n = 2 and 3 and the Verma–Pruess k-ϕ relationships are used.

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Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Reactive Transport Model of Gypsum Karstification in Physically and Chemically Heterogeneous Fractured Media

et al. 2022

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“…With the drive of finding new mineral resources in nature, computational simulation methods have been broadly used to simulate hydrothermal ore‐forming systems within the upper crust of the Earth 1–11 . From the scientific point of view, a hydrothermal ore‐forming system usually involves the following four main processes: a pore‐fluid flow process, a heat transfer process, a mass transport process and a chemical reaction process in the fluid‐saturated porous medium.…”

Section: Introductionmentioning

confidence: 99%

“…From the scientific point of view, a hydrothermal ore‐forming system usually involves the following four main processes: a pore‐fluid flow process, a heat transfer process, a mass transport process and a chemical reaction process in the fluid‐saturated porous medium. This means that for the purpose of computationally simulating a hydrothermal ore‐forming system, it is necessary to mathematically consider a nonlinearly coupled problem containing the abovementioned four main processes, 6,7 so as to derive mathematical governing equations of the coupled problem in the fluid‐saturated porous medium.…”

Section: Introductionmentioning

confidence: 99%

FEM‐based dual length‐scale simulation of hydrothermal ore‐forming systems involving convective flow in fluid‐saturated porous media

Zhao,

Liu

2023

Num Anal Meth Geomechanics

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Hydrothermal ore‐forming systems usually involve coupled processes among pore‐fluid flow, heat transfer, mass transport and chemical reactions in fluid‐saturated porous media. The finite element method (FEM) has provided a powerful tool to solve hydrothermal ore‐forming problems associated with pore‐fluid convective flow. Depending on different interests of research, a hydrothermal ore‐forming system may be simulated at two different length‐scale models, such as a regional (i.e., large length‐scale) model or a deposit (i.e., small length‐scale) model. However, there is an unsolved issue to guarantee the consistency between the applied boundary conditions to a deposit model and the predicted results, at exactly the same location as the boundary of the deposit model, from using the regional model. This paper proposes a FEM‐based dual length‐scale simulation procedure to address this issue. In the proposed procedure, a regional model of coarse mesh is first simulated by the FEM. Since a deposit model is located within the regional model, the applied boundary conditions to the deposit model of fine mesh can be determined from the simulation results of the regional model, so that the consistency can be guaranteed at the common boundary between the deposit model and the regional model. Main outcomes of this study have demonstrated that: (1) the proposed FEM‐based dual length‐scale simulation procedure is suitable and applicable for solving coupled problems involving pore‐fluid flow, heat transfer, mass transport and chemical reactions in fluid‐saturated porous media; (2) the proposed procedure is predictive because it is unnecessary to know the location of an ore deposit prior to the simulation of a hydrothermal ore‐forming system; (3) the boundary condition of a deposit model of fine mesh is consistent with the simulation results obtained from the regional model of coarse mesh, so that the reliability of the simulation results obtained from the deposit model can be ensured.

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“…(5) What was the post-cooling influence of the solidified magma and tectonic faults on the orebody distribution in the oreforming system? Obviously, these five fundamental questions involved in the formation of the Ergu Pb-Zn deposit need to be answered through considering the controlling dynamic processes and mechanisms in a strictly scientific manner [19][20][21][22][23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of the Hydrothermal Metallogenic Mechanism Associated with the Ergu Pb-Zn Deposit, Heilongjiang, China: An Example of Pore-Fluid Convection Controlled Mineralization

Liu,

Zhao

2023

Minerals

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Skarn-hosted deposits are commonly recognized as the consequence of magma intrusion within the Earth’s upper crust. The Ergu Pb-Zn deposit can be regarded as a typical skarn-hosted deposit in the hydrothermal ore-forming system within the central Lesser Xing’an Range (LXR), Heilongjiang, China. Although extensive studies were conducted to understand the ore-forming system associated with the Ergu Pb-Zn deposit through using the traditional geoscience methods, the ore-forming process involved in this deposit has not been justified in a strictly scientific manner to date. In this paper, the hydrothermal ore-forming process of the Ergu Pb-Zn deposit is computationally simulated through using the dual length-scale approach associated with the finite element method (FEM). The related computational simulation results have demonstrated that: (1) the pore-fluid convection provides continuous ore-forming fluid and material sources for the Ergu Pb-Zn deposit at the quartz-Pb-Zn sulfide stage; (2) the convective flow of the pore fluid is the main dynamic mechanism, which controls the temperature, chemical species and pore-fluid velocity distributions in the Ergu Pb-Zn deposit; (3) the localized structure plays a key role in controlling the localized pore-fluid flow pattern, which can further control the location and formation of the orebody grade in the Ergu Pb-Zn deposit; (4) the dual length-scale approach associated with the FEM is very useful in dealing with the computational simulation of the hydrothermal ore-forming mechanism involved in the Ergu Pb-Zn deposit.

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Effects of porosity heterogeneity on chemical dissolution-front instability in fluid-saturated rocks

Cited by 10 publications

References 18 publications

Reactive Transport Model of Gypsum Karstification in Physically and Chemically Heterogeneous Fractured Media

Reactive Transport Model of Gypsum Karstification in Physically and Chemically Heterogeneous Fractured Media

FEM‐based dual length‐scale simulation of hydrothermal ore‐forming systems involving convective flow in fluid‐saturated porous media

Numerical Modeling of the Hydrothermal Metallogenic Mechanism Associated with the Ergu Pb-Zn Deposit, Heilongjiang, China: An Example of Pore-Fluid Convection Controlled Mineralization

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