A numerical approach for modeling coupled Hydro-Mechanical fracture behavior in 2D is presented in this paper. This approach accounts for the strong dependence of the flow characteristics on fracture apertures and offers an anisotropic description of the flow propagation in the fracture. An interface finite element and a constitutive model are developed. In order to validate the applicability of the model to general geomechanic problems, 2D simulations were performed. Results show the good application of the mathematical model and the fundamental hydraulic role played by the fractures.
In diesem Beitrag wird ein Stoffgesetz vorgeschlagen um hydromechanisches Kluftverhalten numerisch zu Modellieren. Dieser Vorgang nimmt die starke Abhangigkeit der Fliesseigenschaften von der Kluftöffnung mit in Anbetracht. Ein Interfaceelement und ein Stoffgesetz wurden entwickelt. Zum validieren der Anwendbarkeit dieses Modells wurden 2D Simulationen durchgefuehrt. Ergebnisse haben gezeigt dass das mathematische Model anwendbar ist und dass Kluefte eine fundamentale hydraulische Rolle spielen.
Une approche numerique pour la modelisation du comportement couple hydro-mecanique des fractures en 2D est presentee dans ce papier. Cette approche prend en compte la forte dependance des caracteristiques du flux de fluide sur les ouvertures des fractures et presente une description anisotrope de la propagation du flux dans la fracture. Un element fini d'interface et un modèle constitutif sont developpes. Dans le but de valider l'applicabilite du modèle à des problèmes generaux de geomecanique, des simulations 2D ont ete realisees. Les resultats montrent la bonne application du modèle mathematique et le rôle hydraulique fondamental joue par les fractures.
Fractured oil reservoirs in petroleum engineering represent since several years an area of study of great interest concerning the production/injection estimation. Since lots of phenomena occur at different scales a global evaluation of the reservoir exploitation field gives up in complexity. In particular, an important problem is represented by the possible effect on productivity due to changes in hydraulic conductivity of the main fractures. Then, the description of single fractures behavior from a geological and a geomechanical point of view represents a subject of central importance.
Lots of studies have been performed during the last years, concerning the behavior of rock fractures; experimental investigations (Barton 1976, Bandis et al. 1981, Gentier 1996) together with modeling works (Goodman et al. 1968, Barton et al. 1985, Boulon et al. 1993) were coupled together with the purpose to offer a general description of fracture behavior from both the hydraulic and the mechanical point of view.
This paper presents a constitutive model (Bart 200), which coupled together these two aspects. The coupling between the hydraulic and the mechanical phenomena is realized combining the cubic law with a non-linear deformation function (hyperbolic) (Goodman et al. 1972, Bandis et al. 1983) to describe the stress-closure/opening curves of the fractures. The coupling behavior under tangential effective stresses is taken into account through the simple Mohr Coulomb linear relation.
From a numerical point of view, fracture modeling is realized through a developed interface contact element implemented in Lagamine finite element code.
