| 摘要 |
A downhole apparatus including a tubular body, first and second ports in a wall of the body, and a fluid pressure-responsive valve arrangement having a locked first configuration associated with a first pressure in which the first port is open and the second port is closed, an unlocked second configuration associated with a second pressure higher than the first pressure in which the first port is open and the second port is closed, and a third configuration associated with a third pressure lower than the second pressure in which the second port is open and the first port is closed. |
