Effect of surface morphology on fluid flow in rough fractures: A review

Abstract

Fracture surface morphology significantly affects fluid flow in rock fractures and has attracted considerable attention in many seepage-related fields. Fluid flow in rough-walled fractures is directly determined by interconnected flow paths and fracture aperture, which are affected by surface roughness, contact areas, and matching degree of fracture surface. Surface roughness plays a major role in affecting fracture flow. Inaccurate assessment and estimation of roughness with anisotropic, scale-dependent, and fractal properties can result in biased or even wrong results in numerical simulations for estimating fracture permeability and describing flow characteristics. Using simplified equations and models may lead to undesired deviations of the results over actual cases. Hence, it is necessary to consider the effect of surface morphology or roughness on fluid flow, which can uncover underlying flow mechanisms inside fractures and advance our understanding of the fracture flow. In this study, we review major fracture geometrical properties and their multiple effects on fluid flow. Surface properties and interior geometries of fractures are separately discussed with their characterizations and descriptions. Linear and nonlinear flow behaviors, as affected by roughness, are extensively discussed, and this is followed by presenting the effect of shear stress, normal stress, and infilling materials. Essential discussions, relevant conclusions, and open questions are presented for future research. The aim of the study is to provide a comprehensive review of the important effects of surface morphology on fluid flow.