Preparation method and application of decompression and augmented injection agent for water injection well

The invention provides a preparation method and application of a decompression and augmented injection agent for a water injection well. The decompression and augmented injection agent comprises the following components: 2-5% of an organic matter degradation agent, 10-15% of a chelating agent, 0.5% of a scale inhibitor, 0.5% of a composite surfactant and the balance of water. The invention further relates to application of the decompression and augmented injection agent for a water injection well. According to the invention, the chelate is subjected to complex reaction with inorganic scales in a water injection string, a near-well bore zone and a deep reservoir, so that the inorganic scales are converted into soluble complexes; the vegetable gum and the polymer residues are degraded by using an organic blocking remover; a composite surfactant with ultra-low interfacial tension is used for stripping residual oil on the surface of stratum rock, and finally plug removal and oil displacement of immediate vicinity