Fractures such as bedding planes, faults, veins and joints are all over crustal rocks. Because of their discontinuities, they dominate the geomechanical and hydrological behaviour of the subsurface rocks. Transport properties in fracture strongly depends on the aperture size and its distribution, thus the ability to investigate fracture aperture would provide extensive amount of information for reservoir characterization and monitoring. This work investigate, using numerical modelling, the effect of aperture heterogeneity on the flow through a fracture network. A fully coupled hydro-mechanical (HM) finite element model is used to reconstruct the behaviour of the fracture aperture. The model accounts for the mechanical deformation of the matrix, and the flow of the fluid in the fractures and rock matrix.