Preparation method of nanofluid for improving oil recovery

The invention discloses a preparation method of a nanofluid for improving oil recovery. The preparation method comprises the following steps: taking 2.0-4.0g of nanopowder, adding 60-80mL of deionized water to the nanopowder and carrying out ultrasonic dispersion at a room temperature for 30-60 minutes; dissolving 2.0g of a silane coupling agent in absolute ethyl alcohol; mixing the nano-base solution with the ethanol solution of the silane coupling agent in a three-neck boiling flask, heating while stirring to the range of 70 to 75 DEG C, reacting for 4-6 hours, filtering, washing by using an anhydrous solvent a plurality of times, and drying in a vacuum drying box at 60-70 DEG C for 12 hours to obtain modified nanoparticles; putting 0.1-0.5g of nanoparticles in the three-neck boiling flask, adding 200-300mL of water, heating to the range of 60-75 DEG C by use of a water bath, mixing a surfactant with PEG (Poly Ethylene Glycol), adding 100mL of mixed solution of the surfactant and the PEG, mechanically stirr