Flow and Transport in Fractured Rocks

Wang, J. S. Y.

doi:10.1002/rog.1991.29.s1.254

Cited by 42 publications

(19 citation statements)

References 154 publications

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“…Because of possible flow channeling along the widest parts of a fracture (Wang, 1991;Tsang and Neretnieks, 1998), aperture variation is important for the permeability in fluid reservoirs. When fluid overpressure of the hydrofracture is the only loading, or the reservoir is subject to remote compression, the aperture of a vertical hydrofracture is greatest in the soft layers and least in the stiff layers Larsen and Gudmundsson, 2010;Gudmundsson et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…For elastic host rocks the aperture normally depends on the fluid pressure in the fracture, the state of stress in the rock, and the mechanical properties of the host rocks. For fractures with varying aperture, fluid flow may be channeled along their widest parts or greatest openings (Wang, 1991;Tsang In the gray limestone layer, the vein is a vertical extension fracture, with the minimum principal compressive stress σ 3 as its normal stress (as is indicated by arrows). In the marl layer, however, the vein is an inclined shear fracture, subject to a higher normal stress σ n and therefore thinner than the vertical part.…”

Section: Discussionmentioning

confidence: 99%

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Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

2013

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Fractures generated by internal fluid pressure, for example, dykes, mineral veins, many joints and man-made hydraulic fractures, are referred to as hydrofractures. Together with shear fractures, they contribute significantly to the permeability of fluid reservoirs such as those of petroleum, geothermal water, and groundwater. Analytical and numerical models show that-in homogeneous host rocks-any significant overpressure in hydrofractures theoretically generates very high crack tip tensile stresses. Consequently, overpressured hydrofractures should propagate and help to form interconnected fracture systems that would then contribute to the permeability of fluid reservoirs. Field observations, however, show that in heterogeneous and anisotropic, e.g., layered, rocks many hydrofractures become arrested or offset at layer contacts and do not form vertically interconnected networks. The most important factors that contribute to hydrofracture arrest are discontinuities (including contacts), stiffness changes between layers, and stress barriers, where the local stress field is unfavorable to hydrofracture propagation. A necessary condition for a hydrofracture to propagate to the surface is that the stress field along its potential path is everywhere favorable to extension-fracture formation so that the probability of hydrofracture arrest is minimized. Mechanical layering and the resulting heterogeneous stress field largely control whether evolving hydrofractures become confined to single layers (stratabound fractures) or not (non-stratabound fractures) and, therefore, if a vertically interconnected fracture system forms. Non-stratabound hydrofractures may propagate through many layers and generate interconnected fracture systems. Such systems commonly reach the percolation threshold and largely control the overall permeability of the fluid reservoirs within which they develop.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

2013

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“…The fastest flow occurring in a hydrologic system can have considerable practical importance, in the context of minimum travel times, if this fast flow transports contaminants in the subsurface. Preferential solute transport has been observed in soils (Ghodrati and Jury, 1990) and unsaturated fractured rocks (Evans and Nicholson, 1987;Wang, 1991), even when the porous medium was seemingly homogenous and lacked well defined preferential paths (Glass and others, 1989c). Preferential solute transport has been shown to be significant for all preferential modes: macropore (Gjettermann and others, 2004), finger (Glass and others, 1988;Hendrickx and others, 1993), and funnel (Kung, 1993) flow.…”

Section: Unsaturated Flow and Preferential Flowmentioning

confidence: 99%

Estimation of Unsaturated Zone Traveltimes for Rainier Mesa and Shoshone Mountain, Nevada Test Site, Nevada, Using a Source-Responsive Preferential-Flow Model

Ebel¹,

Nimmo²

2009

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“…Diverse research efforts have ranged from laboratory-scale studies of discrete fractures to field-scale studies of fracture networks to basin-scale studies of regional ground-water systems (Wang, 1991). A comprehensive assessment of the current level of understanding regarding fluid flow through fractures is presented by Long et al (1996).…”

Section: Introductionmentioning

confidence: 99%

Fractured‐Aquifer Hydrogeology from Geophysical Logs; The Passaic Formation, New Jersey

1997

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The Passaic Formation consists of gradational sequences of mudstone, siltstone, and sandstone, and is a principal aquifer in central New Jersey. Ground-water flow is primarily controlled by fractures interspersed throughout these sedimentary rocks and characterizing these fractures in terms of type, orientation, spatial distribution, frequency, and transmissivity is fundamental towards understanding local fluid-transport processes. To obtain this information, a comprehensive suite of geophysical logs was collected in 10 wells roughly 46 m in depth and located within a .05 km 2 area in Hopewell Township, New Jersey. A seemingly complex, heterogeneous network of fractures identified with an acoustic televiewer was statistically reduced to two principal subsets corresponding to two distinct fracture types: (1) bedding-plane partings and (2) high-angle fractures. Bedding-plane partings are the most numerous and have an average strike of N84° Wand dip of 20° N. The high-angle fractures are oriented subparallel to these features, with an average strike of N79° E and dip of 71 0 S, making the two fracture types roughly orthogonal. Their intersections form linear features that also retain this approximately east-west strike. Inspection of fluid temperature and conductance logs in conjunction with flowmeter measurements obtained during pumping allows the transmissive fractures to be distinguished from the general fracture population. These results show that, within the resolution capabilities ofthe logging tools, approximately 51 (or 18 percent) of the 280 total fractures are water producing. The bedding-plane partings exhibit transmissivities that average roughly 5 m 2 /day and that generally diminish in magnitude and frequency with depth. The high-angle fractures have average transmissivities that are about half those of the bedding-plane partings and show no apparent dependence upon depth. The geophysical logging results allow us to infer a distinct hydrogeologic structure within this aquifer that is defined by fracture type and orientation. Fluid flow near the surface is controlled primarily by the highly transmissive, subhorizontal bedding-plane partings. As depth increases, the high-angle fractures apparently become more dominant hydrologically.

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Flow and Transport in Fractured Rocks

Cited by 42 publications

References 154 publications

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

Effects of mechanical layering on hydrofracture emplacement and fluid transport in reservoirs

Estimation of Unsaturated Zone Traveltimes for Rainier Mesa and Shoshone Mountain, Nevada Test Site, Nevada, Using a Source-Responsive Preferential-Flow Model

Fractured‐Aquifer Hydrogeology from Geophysical Logs; The Passaic Formation, New Jersey

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