| 摘要 |
<p>PISTON TYPE SEAL UNIT A seal unit for movement through a flow conductor for pumpdown piston or well swab service, including a mandrel body, a seal element mounting sleeve disposed for limited travel on the body, and elastic annular seal means secured on the mounting sleeve to seal with the flow conductor wall in response to a first fluid differential across the unit and to permit controlled bypass and load transfer under a second higher differential. The seal means includes spaced annular lips or fins and an annular choke ring which is expanded by limited sleeve movement in response to a fluid pressure differential load applied across the fins. When the pressure differential across the fins exceeds a predetermined value, the sleeve expands the choke ring which assumes a major portion of the pressure differential load relieving the fins to reduce fin wear. As a pumpdown piston, the unit is pumped along a flow conductor to drive a tool train by fluid flow in a direction from the fins toward the choke ring. As a swab, the unit is pulled in the opposite direction to agitate or displace fluid in a well.</p> |
