| 摘要 |
<p>A downhole valve (26) comprises a valve body (32) defining a sealing surface (34) and a flow port (36), a valve member (50) mounted within the valve body and including a sealing arrangement (60), and a protection sleeve (72) mounted within the valve body (32). The valve member is moveable within the valve body from a closed position in which the flow port is closed and the sealing arrangement sealingly engages the sealing surface of the valve body, towards an open position in which the flow port is opened and the sealing arrangement is disengaged from the sealing surface and received within the protection sleeve.</p> |
