The estimation of effective fracture permeability depends mainly on the geometry of the void space between the fracture surfaces. Sometimes, these void spaces are closed partially or totally for various reasons, which create a contact area between the fracture surfaces. These contact areas cause the fluid to follow a tortuous path around them, which reduces the permeability magnitude notably. In this study, a digitised fracture network of a carbonate formation has been used to investigate the impact of contact areas and variable aperture width on the effective fracture permeability by using a discrete fracture networks approach. Moreover, a statistical analysis of a fracture width was used to build a stochastic aperture distribution to evaluate the fluid flow behaviour. Where, the properties of the aperture histogram are the only required parameters for the aperture modelling, in addition to several advantages in the current workflow compared with the former modelling approaches. The results were represented by a correction curve plotted based on the 3D simulation results, which can be used to evaluate the reduction factor in fracture permeability by considering the impact of contact areas in fractures. Furthermore, it can also be utilised for the history-matching process by calibrating the fracture permeability, hence fluid flow behaviour at the well region or the reservoir scale. © 2023 The Authors.