Water injection well anti-swelling/swelled-clay-shrinking agent, preparation method and applications thereof

The invention discloses a water injection well anti-swelling/swelled-clay-shrinking agent, a preparation method and applications thereof, and belongs to the field of oil field injection water, wherein the water injection well anti-swelling/swelled-clay-shrinking agent comprises, by mass, 6.8-12.7% of a hydroxypropyl trimethyl quaternary salt, 6.8-12.7% of potassium chloride, and the balance of water, and the chemical structure formula of the hydroxypropyl trimethyl quaternary salt is defined in the specification. According to the present invention, the volume of the clay particles in the oil well zone and the surrounding oil layer zone can be shrunk through the synergistic effect of the hydroxypropyl trimethyl quaternary salt and the potassium chloride, the hydroxypropyl trimethyl quaternary salt and the potassium chloride are not easily decomposed and do not react with the clay particles, such that the precipitates cannot be generated and the pores in the oil layers cannot be clogged; and the water injection