This paper presents an experimental study on gelation ofaxanthan/chromium(III) system in unconsolidated sandpacks at frontal velocities between 3 and 120 ft/D. High flow resistance developed at specific locations in the sandpacks in experiments conducted at velocities up to 35 ftlD; the locations correlated with velocity. No significant flow resistance developed in the sandpacks at frontal velocities of 83 and 118 ftlD. The effects of flow and shear rates and permeability on development of high flow resistance in the sandpacks are discussed. A conceptual model of the gelation process that incorporates filtration of gel aggregates is presented.