Roughness, Contact Area, and Residual Flow in Unpropped Shale Fractures

Abstract

Mean fracture opening does not uniquely determine flow through a rough, partially closed surface. The location of contacts and constrictions can matter as much as their total extent. This note uses a two-segment synthetic example to demonstrate how identical mean aperture can produce different effective conductivity. The example is then connected to stress-sensitive preserved-shale experiments and rough-contact models. The contribution is a transparent geometric argument and a measurement checklist, rather than a new universal roughness correlation.