| 摘要 |
A method of controlling flow between a flow passage of a tubular string and an annulus includes: constructing a valve having an opening for flow between the passage and annulus; permitting flow through the opening; then preventing flow through the opening in response to applying pressure to the valve; and then mechanically displacing a closure device, thereby allowing flow through the opening. Another method includes applying a pressure differential across a piston of a valve, thereby displacing a closure device; and then displacing the closure device relative to the piston, thereby allowing flow between the passage and the annulus. A valve includes an opening for flow between an interior and exterior of the valve, a closure device for permitting and preventing flow through the opening, and a piston which biases the closure device to displace, the closure device being mechanically displaceable relative to the piston. |
