| 摘要 |
A stage valve for stage cementing of casings in a well bore including a tubular collar and a telescopic tubular sleeve where the sleeve has a piston portion disposed in a collar chamber and the piston portion separates a sleeve port from a collar port in a lower position. In the lower position, the sleeve mechanically engages the collar and is movable to an upper position by a differential hydraulic pressure across the piston portion to an upper position placing the sleeve port and the collar port in fluid communication with one another. In moving to the upper position, the sleeve removes a barrier from a ratchet ring in the collar so that when the sleeve is moved downwardly from an upper position, a ratchet portion on the sleeve engages the ratchet ring in a lower position of the sleeve to lock the sleeve in a closed position. |
