Nanotechnology is widely used in environmental remediation area.However,when nanoparticles are released into the formation and pass through the pore throats,they can be adsorbed on the pore surface,which might cause permeability impairment.A comprehensive study of nanoparticles adsorption behavior is crucial to the optimal design of nanopartilces.In this paper,we conducted core-flood experiments on water wet Berea sandstone to evaluate nanoparticles adsorption behavior.Two typical nanoparticles,hydrophilic nano-structure (NSP) and colloidal nanoparticle (CNP),with respect to different primary diameters,were suspended in brine at 0.05,0.2 and 0.5wt% concentrations.During the core-flood process,the corresponding pressure drop across the cores was recorded to estimate the core permeability damage due to nanoparticles adsorption,as well as study the stability of particle detachment during brine post-flush.The experimental results indicated that both adsorption and desorption occurred during the injection process.The extent of adsorption and retention for nano-structure particles (NSP) was high,while colloidal nanoparticles (CNP) did not adsorb or retain too much.Small particle size and high concentration were both not contributing to high nanoparticle adsorption efficiency.With the moderate particle size and concentration the highest adsorption efficiency was observed.The optimal silica nanoparticles was colloidal nanoparticle (CNP) with customized 18nm particle size,which almost did not affect the permeability of water wet cores.