This paper has as main objective the investigation of the effect of fractures in the process of flow in naturally fractured media. In addition, we investigate the impact of pressure drops, due to the production of oil on the rock permeability and consequently, in the production process. For this, a finite element simulator developed at Tecgraf Institute was used for explicit analysis of fractures in porous and permeable media. After a brief introduction of the formulation and methodology, several numerical models are presented in which attempts have been made to reproduce several production scenarios in fractured reservoirs. Initially, for better observation of the behaviors and analysis of the results some models are presented considering only the decoupled flow simulation of the mechanical process. Then, the coupled analysis of these scenarios is carried out through the development and simulation of more complex models. Another objective of this paper is to present a methodology for determining the equivalent permeability in fractured media through the use of so - called multipliers of porosity and equivalent permeability. The results corroborate the influence of the fractures in the flow processes and indicate the need for hydrogeomechanical analyses for a better evaluation of the production levels in naturally fractured reservoirs.