The invention relates to the technical field of oilfield exploitation, and discloses a nanometer oil-displacing agent for oilfield oil extraction and a preparation method thereof.The nanometer oil-displacing agent takes modified nanometer
silicon dioxide and a surfactant as main components,
polymer macromolecules are modified on the surface of the nanometer
silicon dioxide to serve as a main body of the nanometer oil-displacing agent, and the nanometer oil-displacing agent is prepared. Under the action of the surfactant, the
nano silicon dioxide can flow into the fine
throat and the micro
throat, and the
polymer macromolecules of the branched structure can generate a relatively
strong interaction force with the rock, so that the
polymer macromolecules are firmly adhered to the surface of the rock, the adhesion of
crude oil on the surface of the rock is reduced, a smooth
crude oil channel is constructed, and the flowing pressure of liquid is reduced; and
crude oil fluidity is improved. The structure of the cross-linking agent contains
quaternary ammonium cations, so that the electrostatic repulsion effect between
nano silicon dioxide can be greatly enhanced, aggregation between
nano silicon dioxide and
nano silicon dioxide can be avoided, the interfacial tension can be efficiently maintained, the oil-water interfacial tension is greatly reduced, and the
recovery rate of crude oil is effectively increased.