Stochastic models of fracture networks based on the broad-range fracture length distribution and the long-range fracture correlations.

HR: 14:10h
AN: H52B-03 [PDF]
TI: Stochastic models of fracture networks based on the broad-range fracture length distribution and the long-range fracture correlations.
AU: * Bour, O
EM: olivier.bour@univ-rennes1.fr
AF: GＰsciences Rennes, Universite de Rennes 1, Rennes, 35042 France
AU: Davy, P
EM: philippe.davy@univ-rennes1.fr
AF: GＰsciences Rennes, Universite de Rennes 1, Rennes, 35042 France
AU: de Dreuzy, J
EM: jean-raynald.de-dreuzy@univ-rennes1.fr
AF: GＰsciences Rennes, Universite de Rennes 1, Rennes, 35042 France
AU: Le Borgne, T
EM: tanguy.le-borgne@univ-rennes1.fr
AF: GＰsciences Rennes, Universite de Rennes 1, Rennes, 35042 France
AB: The fact that fractures exist at all scales, and that fracture distributions do not exhibit any obvious length scales except the fracture domain size, poses the question of the relevant model for describing fluid flow in such highly heterogeneous system. Is it possible to use equivalent porous media theory; is it sufficient to consider the major fractures? We tackle these questions by setting up a decision framework for the a priori choice of the modelling framework. Our approach relies on a synthetic fracture-network model based on the geological characteristics of fractures. The first study concerns the connectivity of the fracture network, because connectivity is a prerequisite to any hydraulic property. We then handle the classical hydraulic properties like the equivalent permeability, the flow structure and the well test responses. Non-intuitive results show up. Connectivity is scale-dependent as long as the variance of the fracture length distribution is undefined. It is generally possible to define a homogenization scale mainly function of the fracture density, the fracture length and aperture distributions. This homogenization scale can however be very large splitting the scale range in two parts where fracture networks have different hydraulic behaviours and variabilities. Below the homogenization scale, we have looked for the relevant well-test interpretation framework.
DE: 1829 Groundwater hydrology
DE: 5104 Fracture and flow
DE: 5114 Permeability and porosity
SC: Hydrology [H]
MN: 2003 Fall Meeting