| 摘要 |
<p>A ball drop head, for dropping balls into a tubing or casing string of a well, has a central container (14) with at least one ball carrier ring (38, 40) rotatably disposed therein. A ball cavity (72, 82) is defined in the ring, and a ball (84, 90) is disposed therein. The ball is biased radially inwardly toward the container so that when the ring is rotated to align the cavity with a ball release opening (17, 19) defined in the container, the ball is pushed through the ball release opening to enter and fall through a central opening (16) in the container (14). The ring may be rotated manually or remotely, such as by inflating a pneumatic or hydraulic bellows. Additional rings may be mounted on the container to use in dropping additional balls. <IMAGE></p> |
