The conventional method in investigation and evaluation of oil recovery from petroleum reservoirs is to build a geological model, upscale the model, and perform the simulation. Because of the considerable lack of information especially at early production stages, this procedure encounters high uncertainty. Therefore, based on the physics of fluid flow, several efforts have been made to find simpler methods. The considered procedure in this project is percolation theory which is used for estimation of breakthrough time in a reservoir in the South of Iran. Drawn upon this theory,reservoir is divided into two sections: permeable, impermeable and then percolation scaling laws are used to estimate the key reservoir parameters (Connectivity probability and effective permeability). Since estimating reservoir key parameters and breakthrough time is time consuming, a comprehensive software was developed to facilitate the calculation process. The results showed that percolation theory gave an acceptable prediction for breakthrough time in the investigated reservoir.