Fracture morphology and viscous transport

Schmittbuhl, Jean; Steyer, Alain; Jouniaux, Laurence; Toussaint, Renaud

doi:10.1016/j.ijrmms.2007.07.007

Cited by 85 publications

(62 citation statements)

References 33 publications

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“…The discretisation was thus quite coarse. However, as shown by (Schmittbuhl et al 2008), viscous flow in a fracture is controlled by long wavelengths of the fracture aperture landscape, at least when the fracture is opened. Therefore, as a first approximation, a coarse model was deemed sufficient.…”

Section: Computational Workflowmentioning

confidence: 99%

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Fracture permeability under normal stress: a fully computational approach

Lavrov

2016

J Petrol Explor Prod Technol

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Fractures contribute significantly to the overall permeability of naturally or hydraulically fractured reservoirs. In the cap rock, fractures may provide unwanted pathways for reservoir or stimulation fluids. Predicting fluid flow in naturally fractured rocks under production or fluid injection requires that permeability of a single, rough-walled fracture be well understood and accurately described as a function of the effective stress. The lack of information about the properties of fractures at depth calls for a numerical approach that would enable predicting the fracture permeability as a function of the effective normal stress. Such fully computational approach is developed in this study. The fracture deformation is calculated by solving the contact problem using the finite-element method. At each deformation step, the steady-state fluid flow in the fracture is computed in two orthogonal directions using the lubrication theory approximation, in order to evaluate the permeability and the hydraulic aperture of the fracture. The computational approach is tested on two examples: a 'brittle rock' (linear elastic) and a 'ductile rock' (linear elastic perfectly plastic). Both mechanical and hydraulic behaviours of the fracture under cyclic normal loading are found to be in qualitative agreement with the results obtained in a number of published experimental studies. The computational approach provides an insight into the actual mechanics of the fracture deformation under stress, and the effect of the latter on the permeability. In particular, hysteresis in the fracture roughness is obtained with the 'ductile rock', suggesting that (at least some) fractured rocks may retain 'memory' about their loading history imprinted in the fracture landscapes.

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Section: Computational Workflowmentioning

confidence: 99%

“…It should be noted that, instead of numerical generation of the fracture landscape, a real landscape could be obtained from a real rock sample using, for example, mechanical profilometry (Lespinasse and Sausse 2000) or laser profilometry (MŁynarczuk 2010; Schmittbuhl et al 2008).…”

Section: Computational Workflowmentioning

confidence: 99%

Fracture permeability under normal stress: a fully computational approach

Lavrov

2016

J Petrol Explor Prod Technol

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“…As funções de distribuição de abertura fornecem a probabilidade que pontos com certa abertura ocorram no plano da fratura. As distribuições contínuas do tipo normal (Oron e Berkowitz, 1998;Matsuki et al, 2006;Schmittbuhl et al, 2008;Neuville et al, 2012) e lognormal (Moreno e Tsang, 1994;Zimmerman e Bodvarsson, 1996;Keller, 1998;Nowamooz et al, 2013) têm sido os mais adequados.…”

Section: Lista De Figurasunclassified

“…As distribuições de probabilidade contínuas do tipo normal (Matsuki et al, 2006;Vickers et al, 1992;Yeo et al, 1998;Schmittbuhl et al, 2008;Neuville et al, 2012; Oron e Berkowitz, 1998) e lognormal (Figura 10) (Moreno e Tsang, 1994;Zimmerman e Bodvarsson, 1996;Pyrak-Nolte et al, 1997;Keller, 1998;Wendland e Himmelsbach, 2002;Zheng et al, 2008;Nowamooz et al, 2013;Wang e Cardenas, 2014;Ishibashi et al, 2015) têm sido as mais adequadas nos trabalhos científicos.…”

Section: Abertura Variável: Simulação Estocástica Sequencialunclassified

“…As paredes da fratura são irregulares e possuem propriedades fractais autoafins (Brown e Scholz, 1985;Schmittbuhl et al, 1995;Bonnet et al, 2001;Gouze et al, 2005;Schmittbuhl et al, 2008), em que a variância e a correlação espacial aumentam com o tamanho da fratura (Neuman, 2005). A descrição das rugosidades da fratura usando fractais (Figura 15) tem recebido a atenção dos pesquisadores das áreas de geologia, geofísica, física, matemática aplicada e engenharia.…”

Section: Abertura Variável: Simulação Estocástica Fractalunclassified

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Migração de solutos em basalto fraturado: quantificação experimental em laboratório e validação matemática

Lucas¹

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A avaliação do risco a contaminação e a escolha de técnicas de remediação de poluentes em aquíferos fraturados depende da quantificação dos fenômenos envolvidos no transporte de solutos. A geometria da fratura, usualmente caracterizada pela abertura, é o principal parâmetro que indiretamente controla o transporte nos aquíferos fraturados. A simplificação mais comum desse problema é assumir que as fraturas são um par de placas planas e paralelas, isto é, com uma abertura constante. No entanto, por causa do limitado número de trabalhos experimentais, não está esclarecida a adequabilidade do uso de uma abertura constante para simular o transporte conservativo em fraturas do Aquífero Serra Geral (ASG), Brasil. O objetivo deste trabalho é avaliar a influência da abertura de uma fratura natural do Aquífero Serra Geral sob o transporte conservativo de solutos. Uma amostra natural de basalto fraturado foi usada em um experimento hidráulico e de transporte de um traçador conservativo (escala de laboratório). O campo de abertura foi medido usando a técnica avançada, de alta resolução e tridimensional, chamada microtomografia computadorizada de raios-X. A concentração de traçador medida foi utilizada para validar uma solução analítica unidimensional da Equação de Advecção-dispersão (ADE). O desemprenho do ajuste da ADE às curvas de passagem experimentais foi avaliado para quatro diferentes tipos de aberturas constantes. Os resultados mostraram que o escoamento de água e o transporte de contaminantes pode ocorrer através de fraturas micrométricas, ocasionando, eventualmente, a contaminação do ASG. A abertura de balanço de massa é a única que pode ser chamada propriamente de "abertura equivalente". O uso de aberturas constantes na ADE não permitiu representar completamente o formato das curvas de passagem porque o campo de velocidade não é uniforme e intrinsicamente bidimensional. Portanto, na simulação do transporte deve-se incorporar a heterogeneidade da abertura da fratura.Palavras-chave: Advecção-dispersão, Breakthrough curve, Espectrofotometria, Lei Cúbica, Microtomografia de raios-X. The contamination risk assessment and the choice of suitable cleanup techniques for pollutants in fractured rock depends on the quantification of the transport phenomena. Fracture geometry often described by the apertures is the major parameter that controls indirectly solute transport in fractured rock. The simplest approach is describing fractures as a pair of smooth parallel plates with constant aperture. However, there is a lack of information about the suitability for using a constant aperture for the conservative solute transport prediction in a single fracture of Serra Geral Aquifer (SGA), Brazil. The aim of this work is to evaluate the effect of aperture variability in a natural single rough-walled fracture of Serra Geral Aquifer on conservative solute transport. A natural core of fractured basalt was used for a hydraulic and tracer tests (laboratory scale). The aperture field was measured using the advanced, high-resolution and tr...

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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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Fracture morphology and viscous transport

Cited by 85 publications

References 33 publications

Fracture permeability under normal stress: a fully computational approach

Fracture permeability under normal stress: a fully computational approach

Migração de solutos em basalto fraturado: quantificação experimental em laboratório e validação matemática

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

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