| 摘要 |
A retrievable drill pipe bridge plug (48) includes a packer (132) for setting in the pipe string for engagement with an internal upset therein when an upward force is applied to the packer, means for closing the plug to prevent fluid flow therethrough, and means for opening the plug to permit flow therethrough from below the packer and either into the annulus above the packer, or in the drill string. <IMAGE>
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