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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, F-92852 Rueil Malmaison, France Inst Francais Petr Rueil Malmaison France F-92852 ueil Malmaison, France Inst Francais Petrole, F-92852 Paris, France Inst Francais Petrole ParisFrance F-92852 etrole, F-92852 Paris, France Ecole Normale Super, Geol Lab, F-75231 Paris, France Ecole Normale Super Paris France F-75231 Geol Lab, F-75231 Paris, France
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B3, volume: 106, anno: 2001,
pagine: 3999 - 4016
SICI:
0148-0227(20010310)106:B3<3999:PEDTMD>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH FLUID PRESSURES; TRANSPORT-PROPERTIES; 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, F-92852 Rueil Malmaison, France Inst Francais Petr 1 & 4 Ave Bois Preau Rueil Malmaison France F-92852
Citazione:
G. Simpson et al., "Permeability enhancement due to microcrack dilatancy in the damage regime", J GEO R-SOL, 106(B3), 2001, pp. 3999-4016

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 stress-induced 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 microcrack-induced 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