Initially, gravity drainage mechanism in naturally fractured reservoirs was modeled and validated by solving the available analytical equations (e.g. Firoozabadi and Hauge method in 1990). Block to block interaction effect has been included in this model. Then the effects of different parameters on recovery process were investigated and compared with the production mechanism of different models, such as, dual porosity, dual permeability. This work determined that the most effective parameters on recovery process are block height and matrix permeability. Also in the case of capillary continuity between the blocks, vertical fracture permeability has no effect on recovery process. The main conclusion drawn from this work is that reinfiltration causes a reduction in the production rate; however, it has no effect on ultimate recovery. Also it was concluded that trickled oil from blocks above always prefers to reinfiltrate into the matrix blocks below rather than flowing through the fractures. The following limitations and assumptions apply:
System pressure is constant.
Fluid viscosities are constant.
Fluids are incompressible.
Model is valid only for two phase oil/gas system in the presence of immobile water.