Tool for washing perforations in cased well bore

摘要

Disclosed is a tool for injecting into or washing perforations in a cased well bore. The tool includes an outer housing and an inner mandrel with a fluid passage therebetween. Perforations are cleaned by discharging fluid from the passage into a region between closely spaced cups for maintaining pressure. Also disclosed is a valve system whereby the washing of perforations can be performed either by pumping fluid down the casing or the tubing string. The washing fluid discharged between the cups enters the perforations and is circulated behind the casing until reentering the casing bore through other perforations either above or below the cups. The fluid is returned to the well surface through the tubing by entering either from the tool bottom or through ports in the housing which are in communication with the inner mandrel.