Fluid-flow-driven particle migration through porous networks reflects the interplay between various particle-level forces, the relative size between migrating particles and pore constrictions, and the spatial variability of the velocity field.  Experimental evidence shows that particle migration in radial fluid flow results in self-stabilizing annual clogging patterns when the particle size approaches the constriction size. Conversely, flow localization and flushing instability are observed when the particle size is significantly smaller than the pore-throat size.