Prevention of formation damage due to release and deposition of fines in reservoirs is important to enhance oil production. It is, therefore, essential to know the critical conditions at which particles release and plug the pore channels. This paper presents a physical model of the process of particle deposition in porous network based on a novel experiment in which suspensions of particles were passed through micro capillaries of different diameters [60 and 100 μm] at different velocities and the rate of particle deposition and consequent pressure build up were monitored. An improved 3D trajectory analysis was developed and it was validated by observing the rate of particle deposition in a micro capillary while injecting bentonite suspensions at different velocities and particle concentrations. A criteria is proposed to predict the critical conditions for particle deposition in a micro capillary.