| 摘要 |
A stage valve with particular use in cementing a well bore annulus above an inflatable packer located in a well bore on a liner where the stage valve has pressure operated outer sleeve members for opening a flow port in the stage valve and an inner sleeve member actuated by the trailing plug behind a liquid cement slurry to close the flow port whereupon spring members act on at least one of the outer sleeve members to close off the flow port on the exterior of the stage valve.
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