Abstract
Recent research on naturally fractured reservoirs suggests that microfractures and megafractures are all part of a single population that shows a power-law relation between frequency of occurrence and fracture aperture or length. The objective of this work is to investigate the effective permeability of fracture networks whose fractures obey power-law scaling relations.
For the simple case where each fracture extends through the region of interest, we present a formula that relates effective fracture-network permeability to the distribution of fracture apertures. In this simple case, the effective permeability of the region is dominated by the single largest fracture in the region.
In reality, of course, flow through fractures depends on whether fractures interconnect. Connectivity at one length scale does not relate simply with connectivity at another scale, if fracture properties obey power-law scaling relations. Fracture populations based on frequency/length scaling exponents derived from field data are not guaranteed to interconnect on either the microscopic or megascopic scales. Computer-capacity limitations make it difficult to include enough fractures to model a region even the size of one reservoir grid block. Clustering of fractures into swarms appears to be the key to fracture interconnectivity.
