Experimental Investigation on the Filtering Flow Law of Pre-gelled Particle in Porous Media

Pre-gelled particle (PPG) is a new profile control agent showing high heat resistance and salt tolerance. Single- and double-tube PPG flow experiments were carried out to study the flow law in porous media, the mechanism of profile control, surface deposition and re-migration, plugging deposition and restart, and the permeability variation due to the retention of PPG using sand-packed model. The results showed that PPG, when encountered with throats in the porous media flow, were deformed due to a higher pressure to go through the throats and pressure would reduce once PPG passed through. In this case, the purpose of dynamic profile control was achieved without damage to the formation. The results further showed that PPG owned a smaller coefficient of surface deposition and a higher coefficient of re-migration, so PPG would migrate to the deep formation rather than deposit near the well bore which was favorable to the deep dynamic profile control. The diameter of the re-migration particles increased with the increase in the viscosity and the flow rate of the PPG-carrying fluid and showed a exponential relationship with the product of viscosity and real flow rate of the carrier flow. The pressure gradient needed by the plugged PPG to re-migrate exponentially increased with the ratio of diameters of PPG and throats. The residual permeability coefficient showed a relationship with the amount of particles deposited on the surface in the function of Carman–Kozeny, and it exponentially decreased with an increasing amount of throats blocked by PPG.