Scale dependence of hydraulic and structural parameters in fractured rock

Le résumé fourni par la source

Fundamental understanding of the origin, geometry, extension and scale dependence of fluid pathways in fractured rock is still incomplete. We analyzed deterministic and stochastic fracture networks on different scales based on fluorescent thin sections, borehole images and seismic structures to obtain geometrical network parameters and to estimate fracture permeability in metamorphic and volcanic rock. Additional assumptions like the percolation threshold and calibrations using measured permeability from hydraulic tests and core measurements were included. This leads to well-constrained estimates of permeability and allows a discussion of constraints for unknown quantities and their influence on permeability. The density of connected fracture networks as a function of mean fracture length follows a power law distribution with an exponent of − 1.90, which documents the fractal nature of fractures in crystalline rock. Fracture densities from volcanic rock derived from thin section analysis and BHTV measurements lead to similar results indicating a potentially “universal” power law relation for fractured rocks.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.