Fluid convection and mass transfer in porous sandstones—a theoretical model

Wood, Joanne V.; Hewett, T.A.

doi:10.1016/0016-7037(82)90111-9

Cited by 170 publications

(92 citation statements)

References 8 publications

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“…The orientation of the local flux vector, which is constrained by the fracture orientation at least in one direction, is thus strongly influenced by the fracture network properties, and may lead to very interesting behavior when combined with reactive alteration. In the context of both fractures and heterogeneous porous media, additional insights may be gained from investigations of the interactions between forced-convective/buoyant convective regimes and reactive alteration [e.g., Steefel and Lasaga, 1994;Wood and Hewett, 1982;Graf and Therrien, 2007], accounting for the role of small to intermediate-scale heterogeneity. We are currently investigating reactive alteration of limestone fractures in forced-convective/buoyant convective regimes, and transitions between these regimes, in a study aimed at understanding the genesis of hypogene cave systems.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…Medium alteration is sustained by the gradients in dissolved mineral flux that need to be balanced by mineral sources/sinks associated with dissolution/precipitation. The interaction between complex flow systems (e.g., buoyant convection) and solubility gradients has been considered in previous work [e.g., Wood and Hewett, 1982], but the influence of heterogeneity in the permeability field has not been investigated to date. The mixing zone regimes discussed by Phillips [1991] involve mixing of fluids, each of which contain dissolved species at the solubility limit, where the solubility limit varies with the concentration of a different ion (e.g., salinity) that is not involved in dissolution/precipitation.…”

Section: Introductionmentioning

confidence: 99%

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Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

Chaudhuri

Rajaram

Viswanathan

2008

Water Resources Research

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[1] Precipitation and dissolution reactions within fractures alter apertures, which in turn affects their flow and transport properties. Different aperture alteration patterns occur in different flow and reaction regimes, and they are also influenced by preferential flow resulting from spatial variations in the aperture. We consider the alteration of variable-aperture fractures in gradient reaction regimes, where fluids are in chemical equilibrium with a mineral everywhere but precipitation and dissolution are driven by solubility gradients associated with temperature variations. The temperature field is defined by a geothermal gradient corresponding to a conduction-dominated heat transfer regime. Monte Carlo simulations on computer-generated aperture fields vividly illustrate pattern formation resulting from two-way feedback between fluid flow and reactive alteration. In dissolution-controlled systems, distinct dissolution channels develop along the dominant flow direction, while elongated precipitate bodies form perpendicular to the mean flow direction in precipitation-controlled systems. Aperture variability accelerates the increase and decrease of effective transmissivity by dissolution and precipitation, respectively. The dominance of precipitation versus dissolution is determined by the angle between the mean hydraulic gradient and solubility/temperature gradient. Development of pronounced anisotropy with oriented elongate features is the key feature of aperture alteration in gradient reaction regimes. A stochastic analysis is developed, which consistently predicts general trends in the aperture field during reactive alteration, including the mean, variance, and spatial covariance structure. Our results are relevant to understanding the long-term diagenetic evolution of fractures in conduction-dominated heat transfer regimes and related problems such as emplacement of ocean bed methane hydrates.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

Chaudhuri

Rajaram

Viswanathan

2008

Water Resources Research

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“…As we consider a system in equilibrium with only natural convection, we set τ = 10 4 s, which is the time it takes a fluid particle to traverse the distance L. This gives the reference velocity as V ref = 10 −3 m/s. This is a realistic value, as flow velocities coming from natural convection in a geological permeable layer can be as low as 1 m/year Wood and Hewett (1982). We let the size of the rigid displacements be W ref = 1 m, while the local deformation is no larger than the pore size.…”

Section: Scaling Analysismentioning

confidence: 99%

Upscaling of the Coupling of Hydromechanical and Thermal Processes in a Quasi-static Poroelastic Medium

et al. 2018

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We undertake a formal derivation of a linear poro-thermo-elastic system within the framework of quasi-static deformation. This work is based upon the well-known derivation of the quasi-static poroelastic equations (also known as the Biot consolidation model) by homogenization of the fluid-structure interaction at the microscale. We now include energy, which is coupled to the fluid-structure model by using linear thermoelasticity, with the full system transformed to a Lagrangian coordinate system. The resulting upscaled system is similar to the linear poroelastic equations, but with an added conservation of energy equation, fully coupled to the momentum and mass conservation equations. In the end, we obtain a system of equations on the macroscale accounting for the effects of mechanical deformation, heat transfer, and fluid flow within a fully saturated porous material, wherein the coefficients can be explicitly defined in terms of the microstructure of the material. For the heat transfer we consider two different scaling regimes, one where the Péclet number is small, and another where it is unity. We also establish the symmetry and positivity for the homogenized coefficients.

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“…To do this, we consider a simple model of porosity reduction [e.g., Wood and Hewett, 1982;Lowell et al, 1993] …”

Section: Mixing In the Shallow Discharge Branchmentioning

confidence: 99%

“…Deposition of silica and other minerals are also generally thought to clog fractures and decrease permeability at shallow levels in hydrothermal systems [e.g., White et al, 1956;Wood and Hewett, 1982;Fournier, 1985]; however, the timescale for deposition of silica appears to be too great to result in rapid sealing [Martin and Lowell, 2000]. In seafloor hydrothermal systems, precipitation of anhydrite (CaSO 4 ) may be important [Sleep, 1991;Lowell and Yao, 2002].…”

Section: Introductionmentioning

confidence: 99%

Anhydrite precipitation and the relationship between focused and diffuse flow in seafloor hydrothermal systems

2003

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[1] The mechanisms that control the style of high-temperature hydrothermal discharge at ocean ridge crests are not well understood. Sites of vigorous high-temperature focused venting are often accompanied by nearby regions of low-temperature diffuse flow. Moreover, at some sites, high-temperature fluids are not focused at all and emerge as lowtemperature diffuse flow as a result of conductive cooling and/or mixing with cooler seawater, whereas at others discharge has evolved from low-temperature diffuse flow to high-temperature focused flow over a number of years. To better understand the mechanisms that control these discharge styles, we construct a two-branch single-pass hydrothermal circulation model to investigate the role of anhydrite precipitation in mixing between deep-seated, high-temperature, sulfate-free upflow and cooler, sulfate-rich seawater circulating through permeable pillow basalts. We also estimate the width of the impermeable anhydrite barrier between focused and diffuse discharge. The model results suggest that focusing can occur in a matter of years provided the permeability in the deep part of the discharge zone is greater than or equal to that of the mixing zone and the permeability of the mixing zone is initially high ($10 À11 -10 À12 m 2 ). If one of the previous conditions is not met, only diffuse flow venting will occur. The width of the impermeable barrier resulting from the precipitation of anhydrite ranges between 1 and 100 m, thus permitting diffuse flow to occur in close proximity to focused discharge.INDEX TERMS: 3015 Marine Geology and Geophysics: Heat flow (benthic) and hydrothermal processes; 3035 Marine Geology and Geophysics: Midocean ridge processes; 5114 Physical Properties of Rocks: Permeability and porosity; 8135 Tectonophysics: Hydrothermal systems (8424); KEYWORDS: seafloor hydrothermal systems, anhydrite precipitation, permeability, diffuse venting, black smokers Citation: Lowell, R. P., Y. Yao, and L. N. Germanovich, Anhydrite precipitation and the relationship between focused and diffuse flow in seafloor hydrothermal systems,

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Fluid convection and mass transfer in porous sandstones—a theoretical model

Cited by 170 publications

References 8 publications

Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

Alteration of fractures by precipitation and dissolution in gradient reaction environments: Computational results and stochastic analysis

Upscaling of the Coupling of Hydromechanical and Thermal Processes in a Quasi-static Poroelastic Medium

Anhydrite precipitation and the relationship between focused and diffuse flow in seafloor hydrothermal systems

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