| 摘要 |
A straddle tool is disclosed which ensures sequential setting of the packing elements through the use of lost motion mechanisms. Once the lower pack-off has been set, the upper one is set and an internal valve is opened to allow flow through the tool to actuate a downhole tool, such as an inflatable packer. An anchor prevents actuation of the pack-off tool unless it is extended into a profile for support of the tool. Inadvertent settings of the pack-off tool are prevented, such as in oversized casing where the anchors are already fully extended, by virtue of a distance-sensing mechanism on the tool. When a large distance is sensed by one or more sensors, the mandrel is locked to the setting collars, preventing relative movement which could set the pack-off elements.
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