In oil industry, excess water production is a major problem that leads to early well abandonment and unrecoverable hydrocarbon. Gel treatments at the injection wells to plug the thief zones are cost-effective methods to improve sweep efficiency and reduce excess water production. Yet, the stability of gel particle when subjected to high temperature still remain questionable. A new waterflood experiment with the introduction of grafted bentonite particles as the plugging agent is proposed to provide a solution to this uncertainties. Propagation and permeability modification process by grafted bentonite particles involved in the treatment and conditioning of high permeability porous media is investigated. The permeability modification and resistance factor are inferred by measurements of pressure differentials with time across the sandstone core by using coreflood experiment. Propagation of grafted bentonite particles are observed by using Scanning Electron Microscope (SEM). The effective mechanism of the consecutive plugging process during the flow of grafted bentonite particles through the sandstone core are identified and the best-estimate values of their rate coefficient are determined. This study reveals valuable information about the functional trend of porous media plugging by grafted bentonite particles which is essential for successful mitigation of formation plugging in the field.