Geometry, percolation and transport properties of fracture networks derived from line data

Abstract : In most geological instances, 2-D or 3-D fracture distributions are not available from field data. We show here that when data relative to fractures are collected along a line such as a road or a well, estimations can be given to the major geometrical properties of the corresponding fracture networks, such as the volumetric density of fractures, their percolation character and their macroscopic permeability. All these formulae are analytical and can be split into two parts; the first one can be derived from the measured data, while the second one requires some assumption on the lateral extension of the fractures and on their permeability. All these techniques are applied to fractures located in the Baget watershed. They are also validated on a granite block whose structure is fully known. Extensions are proposed for networks with variable permeabilities and polydisperse fractures.