| 摘要 |
This invention relates to an apparatus for controlling the motion of a string of tubulars in a wellbore. In milling a tubular with a downhole mill, using too much weight on the mill and/or advancing the mill too quickly can result in inadequate milling, inefficient milling, and damage to the mill, its associated equipment, and the item to be milled. In offshore milling operations, a mill lifted away from a tubular being milled, e.g. by a swell at the water's surface that lifts a boat or barge from which the milling system is suspended, can be slammed back into the tubular being milled as the swell passes and the boat is effectively lowered. This is particularly undesirable.
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