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Titolo: Permeability enhancement due to microcrack dilatancy in the damage regime
Autore: Simpson, G; Gueguen, Y; Schneider, F;
 Indirizzi:
 Inst Francais Petr, F92852 Rueil Malmaison, France Inst Francais Petr Rueil Malmaison France F92852 ueil Malmaison, France Inst Francais Petrole, F92852 Paris, France Inst Francais Petrole ParisFrance F92852 etrole, F92852 Paris, France Ecole Normale Super, Geol Lab, F75231 Paris, France Ecole Normale Super Paris France F75231 Geol Lab, F75231 Paris, France
 Titolo Testata:
 JOURNAL OF GEOPHYSICAL RESEARCHSOLID EARTH
fascicolo: B3,
volume: 106,
anno: 2001,
pagine: 3999  4016
 SICI:
 01480227(20010310)106:B3<3999:PEDTMD>2.0.ZU;2Q
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 HIGH FLUID PRESSURES; TRANSPORTPROPERTIES; WESTERLY GRANITE; REGIONAL METAMORPHISM; COMPRESSIVE STRESS; ROCKS; DEFORMATION; EVOLUTION; CRACKS; MODELS;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Physical, Chemical & Earth Sciences
 Citazioni:
 50
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Simpson, G Inst Francais Petr, 1 & 4 Ave Bois Preau, F92852 Rueil Malmaison, France Inst Francais Petr 1 & 4 Ave Bois Preau Rueil Malmaison France F92852



 Citazione:
 G. Simpson et al., "Permeability enhancement due to microcrack dilatancy in the damage regime", J GEO RSOL, 106(B3), 2001, pp. 39994016
Abstract
A three dimensional microscopically based permeability model incorporatinginelastic deformation has been developed to account for the modification of transport properties due to fracturing. The basic hypothesis investigatedis that permeability enhancement during brittle deformation is caused by the formation of dilatant microcracks which are associated with friction sliding on a preexisting random population of shear cracks. Additional dilatancy, produced as a result of frictional sliding over asperities, is also accounted for by the introduction of a crack roughness parameter. Linear elastic fracture mechanics is used to calculate the evolution of crack length and crack area as a function of applied stress and fluid pressure. After making a geometrical simplification the microcrack parameters derived from the deformation model can be used to calculate the permeability tensor assumingthat fluid transport results from Poiseuille flow through a connected distribution of cracks. The model enables investigation of the macroscopic permeability variation as a function of two loading parameters, three constant material parameters, and the crack roughness parameter. Results demonstratethat permeability is a smooth but strongly increasing: (near power law) function of the Terzaghi effective stress ratio and is strongly dependent on the initial crack density, Young's modulus, the friction coefficient, and the effective confining: pressure. Numerical results are in quantitative agreement with published experimental measurements and display behavior similar to results obtained with a relatively simple analytical model. The model enables calculation of the degree of stressinduced anisotropy, which is shown is be relatively small (< x 10) for resonable effective stress ratios. The modeling presented provides a quantitative tool with which the effects of microcrackinduced permeability enhancement can be investigated within the broader context of coupled fluid flow and brittle deformation in the crust.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 17:50:04