The oil reservoirs exploitation processes are one of very important steps of petroleum industry. The rentability of investor reservoir is related to correct planning and accurate understanding of rock properties and liquids flow in porous media. The complexity of porous media contains hydrocarbon materials, with phases changes related to thermo-physiochemical phenomena, make the classical methods used to study the reservoir recovery are inaccurate and insufficient to predict the performance and behavior of reservoir. Recently, simulation and modeling are used to decrease the risks in the decision of the optimal recovery method, and achieve the best possible rentability. This method provides predictive capacity help us to better understanding of reservoir. By the suitable input data, we can solve the calibrated mathematical model analytically or numerically. We present in this research the formulation of mathematical model of isotropic-one dimension reservoir with single phase fluid flow. The numerical solution, the application of this model, and the mechanism of pressure diffusivity along productive formation, will be presented to simulate a reservoir with injection and production wells.