| 摘要 |
A differential fill valve assembly for application in float collars or shoes in a well casing can provide locking mechanisms to limit premature movement of an activating sleeve while facilitating desired advancement of the activating sleeve. The valve assembly comprises a backpressure flapper valve and an activating sleeve slidably disposed within a housing. The activating sleeve initially maintains the flapper valve in an open position while the activating sleeve is maintained in its position by upper and/or lower lock rings on either side of a shoulder of the activating sleeve. A tripping ball is dropped to seat in the activating sleeve. Pressure applied on the ball moves the activating sleeve downward, releasing the backpressure flapper valve, after which the tripping ball exits the bottom of the assembly. The lower lock ring maintains the activating sleeve in its lower position. |
