Estimating permeability and modelling fluid flow are essential concepts for geotechnical studies, reservoir studies and constructing dam. In many formations especially when the rock matrix is impermeable, fractures are the main way for carrying fluid. Discrete Fractures network has complicated structures generally, so generating certain models of discrete fractures network is difficult. Theoretical and empirical studies have shown that 3D models of fractures which are generated randomly have more pragmatic results. So generating 3D models of fractures is the first step for studding fluid flow pattern. As the purpose of this study is 3D numerical modeling of Hydro-mechanical behavior of a fractured reservoir –A case study in South Pars gas reservoir, 3D model of a fractured reservoir was generated using interpreted field data and FracIUT 3D computer code, at first. FracIUT 3D code based on probabilistic distribution functions for each parameters of joint sets and using iterative Monte Carlo simulations generates fractures network. Then effect of ambient stresses on fractures was analyzed, using SFluIUT 3D computer program. After calculating stress on each fracture and generating 3D models of fractures, flow condition using FluIUT 3D computer code based on pipe network was modelled. After flow modelling, permeability tensor components in 3D media in fractured reservoir using sensitivity analyze were estimated. Permeability changes in 2D condition was compared with 3D condition which permeability value in 3D condition was bigger than 2D condition because of larger density of joint sets in 3D condition.
