Fractures are the main channels of production/injection in naturally fractured reservoirs; therefore the fracture permeability is a key parameter to production optimization and reservoir management. Pressure depletion in naturally fractured reservoirs can result in effective stress change that, in turn, can change fracture permeability. Recent work described a new model employing a fully coupled poroelastic displacement discontinuity method with a nonlinear fracture deformation model and showed that fracture permeability can decrease or increase with decreasing pore pressure depending on in situ stress conditions. The model application featured in this paper is a radial composite reservoir with a dual porosity inner region surrounded by a homogeneous matrix of infinite extent. Similar models in the literature have not included stress dependent fracture permeability. In this model, fracture permeability values vary spatially and with time. The resulting pressure transient behavior is shown for several cases of potential practical interest including both fracture permeability loss and enhancement. The model behavior offers new explanations for commonly observed pressure transient responses and underscores a need for additional rock mechanical properties to ensure conclusive analysis of these systems. Field data experiences indicate that without such data, interpretations may be seriously flawed.

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