The architecture and geometry of the void space of a porous medium and its complementary grain matrix determine several macroscopic properties of the rock such as porosity, relative permeability and capillary pressure. Therefore, it is important to study the microscopic structure of the reservoir pores and understand the physical fluid displacements through them. One approach to this problem is pore-scale modeling that requires a detailed understanding of the physical processes occurring on the pore scale and a complete description of the morphology of the pore space. The pore scale network is a representation of the void space of the reservoir rock. Wide voids of the reservoir rocks are represented by the pore bodies which are interconnected by narrow spaces called pore throats. The key results of the network model are the ability to predict the trend in relative permeability, capillary curves, fractional flows and residual saturations with capillary number and viscosity ratio and to reproduce the displacement patterns.