Stress‐mediated closing of fractures: Impact of matrix diffusion

Neretnieks, Ivars

doi:10.1002/2013jb010645

Cited by 14 publications

(20 citation statements)

References 38 publications

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“…For stagnant fluids, precipitation will occur in the contact zone periphery, leading to accelerated growth of the contact zones and in turn reduced contact stresses. A critical stress at which pressure solution ceases could prevent a sealing state [Yasuhara and Elsworth, 2004;Taron and Elsworth, 2010]; its applicability, however, is a subject of debate [e.g., Neretnieks, 2014].…”

Section: Discussionmentioning

confidence: 99%

“…The physical bounds for values of c ( x ) are as minimum and maximum, respectively, the temperature‐dependent equilibrium concentration of the free fluid, c eq , and the stress‐enhanced equilibrium concentration in the grain‐contact zone, c eq,s . The latter scales exponentially with the contact stress (Figure ), and it follows that, after replacing the molecular volume by the molar volume, and the gas constant by the Boltzmann constant in equation (26) of Neretnieks [],

c_{normaleq, s} (σ^{'}) = c_{eq} \exp ((), \frac{σ^{'} Ω_{s}}{k_{B} T})

…”

Section: Methodsmentioning

confidence: 99%

“…While results of this study indicate that there exists no unique relationship between hydraulic aperture and contact ratio, the mean mechanical aperture of the elastically deformed pore space was shown to fit equation (15) independently of pressure or temperature; see Figure 13b. The model presented herein, analogous to Neretnieks [2014], does not assume the existence of a critical stress; i.e., pressure solution acts to dissolve any surface roughness in the long time limit. It follows that 1 = 0, as no residual aperture is being accounted for.…”

Section: The Relationship Between Aperture and Contact Ratiomentioning

confidence: 99%

“…Macroscopic models [ Yasuhara and Elsworth , ; Taron and Elsworth , ; Zhao et al , ; Neretnieks , ] that quantify pressure solution compaction in rock fractures often have their origin in the modeling of granular aggregates and resort to several approximations: (1) the use of an average, uniform value for contact stress; (2) the idealization of fracture contact as a circular or square shape; (3) uniform dissolution over the contact zone; (4) evaluation of the hydraulic aperture as a mean of local apertures; and (5) assumption of no elastic deformation of the pore space.…”

Section: Introductionmentioning

confidence: 99%

“…Macroscopic models [Yasuhara and Elsworth, 2004;Taron and Elsworth, 2010;Zhao et al, 2014;Neretnieks, 2014] that quantify pressure solution compaction in rock fractures often have their origin in the modeling of granular aggregates and resort to several approximations: (1) the use of an average, uniform value for contact stress;…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic sealing due to pressure solution contact zone growth in siliciclastic rock fractures

2015

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Thermo‐hydro‐mechanical‐chemical simulations at the pore scale are conducted to study the hydraulic sealing of siliciclastic rock fractures as contact zones grow driven by pressure dissolution. The evolving fluid‐saturated three‐dimensional pore space of the fracture results from the elastic contact between self‐affine, randomly rough surfaces in response to the effective confining pressure. A diffusion‐reaction equation controls pressure solution over contact zones as a function of their emergent geometry and stress variations. Results show that three coupled processes govern the evolution of the fracture's hydraulic properties: (1) the dissolution‐driven convergence of the opposing fracture walls acts to compact the pore space; (2) the growth of contact zones reduces the elastic compression of the pore space; and (3) the growth of contact zones leads to flow channeling and the presence of stagnant zones in the flow field. The dominant early time compaction mechanism is the elastic compression of the fracture void space, but this eventually becomes overshadowed by the irreversible process of pressure dissolution. Growing contact zones isolate void space and cause an increasing disproportion between average and hydraulic aperture. This results in the loss of hydraulic conductivity when the mean aperture is a third of its initial value and the contact ratio approaches the characteristic value of one half. Convergence rates depend on small‐wavelength roughness initially and on long‐wavelength roughness in the late time. The assumption of a characteristic roughness length scale, therefore, leads to a characteristic time scale with an underestimation of dissolution rates before and an overestimation thereafter.

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Section: Discussionmentioning

confidence: 99%

c_{normaleq, s} (σ^{'}) = c_{eq} \exp ((), \frac{σ^{'} Ω_{s}}{k_{B} T})

…”

Section: Methodsmentioning

confidence: 99%

Section: The Relationship Between Aperture and Contact Ratiomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydraulic sealing due to pressure solution contact zone growth in siliciclastic rock fractures

2015

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Thermo‐Hydro‐Chemical‐Mechanical Effects on Fracture Transmissivity

2023

Fluid Flow in Fractured Rocks

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Modeling of Solute Transport in a 3D Rough-Walled Fracture–Matrix System

2017

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Fluid flow and solute transport in a 3D rough-walled fracture-matrix system were simulated by directly solving the Navier-Stokes equations for fracture flow and solving the transport equation for the whole domain of fracture and matrix with considering matrix diffusion. The rough-walled fracture-matrix model was built from laser-scanned surface tomography of a real rock sample, by considering realistic features of surfaces roughness and asperity contacts. The numerical modeling results were compared with both analytical solutions based on simplified fracture surface geometry and numerical results by particle tracking based on the Reynolds equation. The aim is to investigate impacts of surface roughness on solute transport in natural fracture-matrix systems and to quantify the uncertainties in application of simplified models. The results show that fracture surface roughness significantly increases heterogeneity of velocity field in the rough-walled fractures, which consequently cause complex transport behavior, especially the dispersive distributions of solute concentration in the fracture and complex concentration profiles in the matrix. Such complex transport behaviors caused by surface roughness are important sources of uncertainty that needs to be considered for modeling of solute transport processes in fractured rocks. The presented direct numerical simulations of fluid flow and solute transport serve as efficient numerical experiments that provide reliable results for the analysis of effective transmissivity as well as effective dispersion coefficient in rough-walled fracture-matrix systems. Such analysis is helpful in model verifications, uncertainty quantifications and design of laboratorial experiments.

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Stress‐mediated closing of fractures: Impact of matrix diffusion

Cited by 14 publications

References 38 publications

Hydraulic sealing due to pressure solution contact zone growth in siliciclastic rock fractures

Hydraulic sealing due to pressure solution contact zone growth in siliciclastic rock fractures

Thermo‐Hydro‐Chemical‐Mechanical Effects on Fracture Transmissivity

Modeling of Solute Transport in a 3D Rough-Walled Fracture–Matrix System

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