Effects of stress on the 2-D permeability tensor of natural fracture networks
Effects of stress on the 2-D permeability tensor of natural fracture networks
The effects of stress on the 2-D permeability tensor of natural fracture networks were studied using a numerical method (Universal Distinct Element Code). On the basis of three natural fracture networks sampled around Dounreay, Scotland, numerical modelling was carried out to examine the fluid flow in relation to the variations in burial depth, differential stress and loading direction. It was demonstrated that the permeability of all the networks decreased with depth due to the closure of aperture. The permeability approached the minimum value at some depth below which little further variation occurred. Also, differential stress had a significant effect on both the magnitude and direction of permeability. The permeability generally decreased with increasing major horizontal stress for a fixed minor horizontal stress, but the various networks considered showed different behaviours. A factor, termed the average deviation angle of maximum permeability (Am), was defined to describe quantitatively the deviation degree of the direction of the major permeability component from the applied major stress direction. For networks whose behaviour is controlled by set(s) of systematic fractures, Am is significantly greater than zero, whereas those comprised of non-systematic fractures have Am close to zero. In general, fractured rock masses, especially those with one or more sets of systematic fractures, cannot be treated as equivalent porous media. Specification of the geometry of the network is a necessary, but not sufficient, condition for models of fluid flow. Knowledge of the in situ stress, and the deformation it induces, is necessary to predict the behaviour of the rock mass.
fractures, numerical modelling, permeability
912-924
Zhang, Xing
e92abcc2-6163-40b0-9b53-0a61bdf864d7
Sanderson, David J.
5653bc11-b905-4985-8c16-c655b2170ba9
June 1996
Zhang, Xing
e92abcc2-6163-40b0-9b53-0a61bdf864d7
Sanderson, David J.
5653bc11-b905-4985-8c16-c655b2170ba9
Zhang, Xing and Sanderson, David J.
(1996)
Effects of stress on the 2-D permeability tensor of natural fracture networks.
Geophysical Journal International, 125 (3), .
Abstract
The effects of stress on the 2-D permeability tensor of natural fracture networks were studied using a numerical method (Universal Distinct Element Code). On the basis of three natural fracture networks sampled around Dounreay, Scotland, numerical modelling was carried out to examine the fluid flow in relation to the variations in burial depth, differential stress and loading direction. It was demonstrated that the permeability of all the networks decreased with depth due to the closure of aperture. The permeability approached the minimum value at some depth below which little further variation occurred. Also, differential stress had a significant effect on both the magnitude and direction of permeability. The permeability generally decreased with increasing major horizontal stress for a fixed minor horizontal stress, but the various networks considered showed different behaviours. A factor, termed the average deviation angle of maximum permeability (Am), was defined to describe quantitatively the deviation degree of the direction of the major permeability component from the applied major stress direction. For networks whose behaviour is controlled by set(s) of systematic fractures, Am is significantly greater than zero, whereas those comprised of non-systematic fractures have Am close to zero. In general, fractured rock masses, especially those with one or more sets of systematic fractures, cannot be treated as equivalent porous media. Specification of the geometry of the network is a necessary, but not sufficient, condition for models of fluid flow. Knowledge of the in situ stress, and the deformation it induces, is necessary to predict the behaviour of the rock mass.
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Published date: June 1996
Keywords:
fractures, numerical modelling, permeability
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Local EPrints ID: 76145
URI: http://eprints.soton.ac.uk/id/eprint/76145
ISSN: 0956-540X
PURE UUID: 20bac167-4907-4738-917c-b063dcb3451a
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Date deposited: 11 Mar 2010
Last modified: 10 Jan 2022 02:53
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Author:
Xing Zhang
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