Particle migration through porous media is an effective method for improving the characteristics of the surrounding medium by reducing the permeability and improving its mechanical properties. The capacity of drilling fluid/suspension to penetrate into the medium depends on the state of the porous media, rheology of the injecting fluid and the boundary stresses. Additionally, the critical aspects that also govern the migration phenomenon are the hydrodynamic forces of the fluid and the constriction size distribution of the porous medium. The trivial process that occurs during fluid injection is that the particulates present in the suspension gets filled in the void spaces thereby blocking the flow path. Even though the particle deposition in the pore throat is a transient process which results in decreasing the overall porosity, the spatial variation of the porosity can be only obtained only after the steady state is reached. Further, the various filtration zones formed during the migration process and the pressure variation in each of these zones are not clearly understood. In this study, a specially designed laboratory experimental setup capable of visualising the flow of suspension through the granular medium is utilised to understand the effect of injecting fluid viscosity and packing density on the particle migration characteristics both spatially and temporally. Finally, the critical zones that are formed during the migration process are also ascertained.