| 摘要 |
<p>A well tool (220), eg. a packer, a firing head or a release sub, Comprises a member (52) slidable relative to the housing (38) of the tool, to actuate the tool. A separate actuator assembly (182) is receivable in the tool and includes a chamber (219) at a pressure lower than the well pressure. Means (55; 196) are provided for applying well pressure to one side of the member and said chamber pressure to the other side of the member, to cause the member to slide to actuate the tool. Advantageously, the member (52) is a sleeve or piston.</p> |
