The colloidal dispersion gels (CDG) were prepared by low concentration partiallyhydrolyzed polyacrylamide with different molecular weights and aluminum citrate. Theproperties of CDG were investigated by the Oswald capillary viscometer

ultrafine sizeanalyzer and theflow experiment. The resultsshowedthatthe viscosity of CDG islowerthanthat of hydrolyzed polyacrylamide (HPAM) and the viscosity of CDG decreases withincreasing the reaction time. The particle diameter of CDG with HPAM molecular weights of 4×106and 1.4×107 was determined to be 460 and 510 nm

respectively. The flow resistance of CDG

which generally increased with increasing HPAM molecular weights and concentration

is much larger than that of HPAM solutions in the core. The flow resistance of the CDG in lower-permeability core was increased more quick than that of the CDG in higher-permeability core. The flow resistance of CDG in the core was associated with the moleculare weight and concentration of HPAM and the permeability of the core. CDG is able to increase the flow resistance in the core effectively.