| 摘要 |
A downhole anchor for preventing rotational movement of a member within a we ll has a central tubular member (10), a slip housing (20) and a drag assembly (13) disposed about the tubular member. The slip housing carries at least two slip members (26, 27, 28), each slip member being rotatable about an axis substantially parallel to the central axis of the tubular member between a retracted position against the housing, and an extended position. The drag assembly is mounted on and rotatable about the tubular member and carries drag means (14). An actuator drives the rotation of the slip member in response to the rotation of the drag assembly about the tubular member. Drag means comprise a spring loaded drag block to frictionally engage a well casing, or, alternatively, unique vane members for reacting with a viscous fluid trapped between the vane members and well casing to cause drag .
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