With the extraction of hydrocarbons from reservoirs, fractures will gradually close and their permeabilities will be reduced. Therefore, fracture conductivity will change dynamically during hydrocarbon extraction. The main objective of this study is to develop a new semi-analytical model to simulate the flow inside a homogenous porous medium containing discretely distributed fractures with dynamic conductivities. Based on a dynamic-conductivity model, the pressure and pressure-derivative characteristics of a well on or near discrete dynamic-conductivity fractures were simulated. The results show that four flow regimes can be identified for a well near a dynamic-conductivity fracture. Dips in the pressure-derivative curves in the transitional flow period were observed as soon as pressure disturbances reached a fracture. In addition, humps caused by the effects of dynamic conductivity were observed after the transitional flow period. Wider and deeper dips were found on the pressure/pressure-derivative curves of a well surrounded by multiple fractures. The novel model presented here can provide a tool for elucidating the flow mechanisms of fluids in closed rectangular reservoirs with discretely dynamic-conductivity fractures.