STRUCTURE, FLOW, AND GENERALIZED CONDUCTIVITY SCALING IN FRACTURE NETWORKS

We present a three-dimensional (3-D) model of fractures that within th e same framework, allows a systematic study of the interplay and relat ive importance of the two key factors determining the character of flo w in the system. The two factors of complexity are (1) the geometry of fracture plane structure and interconnections and (2) the aperture va riability within these planes. Previous models have concentrated on ea ch separately. We introduce anisotropic percolation to model a wide ra nge of fracture structures and networks. The conclusion is that either of these elements, fracture geometry and aperture variability, can gi ve rise to channeled flow and that the interplay between them is espec ially important for this type of flow. Significant outcomes of our stu dy are (1) a functional relationship that quantifies the dependence of the effective hydraulic conductivity on aperture variability and on t he network structure and fracture element density, (2) a relation betw een aperture variability and the Peclet number, and (3) a basis for a new explanation for the field-length dependence of permeability observ ed in fractured and heterogeneous porous formations.