| 摘要 |
An apparatus for use in launching cement plugs in a well cementing operation, comprising: —a cylinder (104) having ports (106) defined in a portion of the wall thereof; —a piston (108) slideably received in the bore of the cylinder below the ports; and —an actuator (110) extending from the piston through the cylinder and operable by the piston for launching a plug from the apparatus into the well; wherein the apparatus further comprises an elongate sleeve valve member located in the cylinder above the piston, the sleeve valve member (112) comprising at least one ball seat (114a-114c) for receiving a ball to block the interior of the cylinder, sleeve ports formed in the sleeve above the ball seat, and a spacer (118) extending between the ball seat and the piston. |
