Bottom sand washing service tool for sand prevention of small cased well

The utility model relates to a bottom sand washing service tool for sand prevention of a small cased well. The upper port of the tubular column guide shoe is screwed with a ball seat; the upper port of the ball seat is provided with a ball seat female thread; male threads are arranged at the lower end of the ball seat; a ball seat throat is arranged at the upper end of the ball seat center hole; ahorn mouth with a small upper part and a large lower part is arranged below the throat of the ball seat and is sealed with a steel ball; the lower edge of the steel ball abuts against the center of the baffle. A plurality of baffle water permeable holes are uniformly distributed in the center and the circumference of the baffle; a spring is supported at the lower end of the baffle and arranged onthe centralizing flow guide sleeve in a sleeving mode, a certain distance is reserved between an upper end opening of the centralizing flow guide sleeve and the bottom of the baffle, the lower end ofthe centralizing flow guid