Well system

摘要

Disclosed is a well system, particularly adapted to pumpdown operation in which lowering an easily retrievable tool string, including an improved standing valve, into an improved foot valve opens the foot valve for production flow. The standing valve prevents flow into the producing formation when the foot valve is open. Lifting the tool string from the foot valve closes the foot valve to protect the producing formation when the tool string is retrieved. Means are provided retaining the foot valve in open or closed positions. Provisions are made for pumping into the formation around both the standing valve and foot valve when closed.