An experimental investigation on the mechanism of fluid flow through single rough fracture of rock

Abstract

The structure of fractures in nature rock appears irregular and induces complicated seepage flow behavior. The mechanism and quantitative description of fluid flow through rock fractures is a difficult subject that has been greatly concerned in the fields of geotechnical, mining, geological, and petroleum engineering. In order to probe the mechanism of fluid flow and the effects of rough structures, we conducted a few laboratory tests of fluid flow through single rough fractures, in which the Weierstrass-Mandelbrot fractal function and PMMA material were employed to produce the fracture models with various fractal roughnesses. A high-speed video camera was employed to record the fluid flow through the entire single rough fracture with a constant hydraulic pressure. The properties of fluid flow varying with the fracture roughness and the influences of the rough structure were analyzed. The components of flow resistance of a single rough fracture were discussed. A fractal model was proposed to relate the fluid resistance to the fracture roughness. A fractal equivalent permeability coefficient of a single rough fracture was formulated. This study aims to provide an experimental basis and reference for better understanding and quantitatively relating the fluid flow properties to the structures of rock fractures.