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US 4,669,541 AGranted
Stage cementing apparatus
AssigneeDowell Schlumberger Incorporated
InventorHarold S. Bissonnette
Life of this patent
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AssigneeDowell Schlumberger Incorporated
InventorHarold S. Bissonnette
Estimating the term…
A stage collar for stage cementing a well casing includes a slidable closing sleeve having ports alignable with ports in the stage collar case. These closing sleeve and stage collar ports communicate with an annulus around the well casing when the stage collar is open. A shift sleeve closes the ports during running in and is actuable by simple drill pipe movements to open and reclose the stage collar ports. The shift sleeve is operably coupled to the closing sleeve by a latch ring which locks the closing sleeve closed and cooperated therewith to form a smooth and substantially uniform inner stage collar bore. The drill pipe is operably connected to the stage collar by a screw-in or latch-in shifting tool which cooperates with the stage collar elements to form a fluidtight passage from the drill pipe to the annulus without entering the well casing interior. A dual stage shifting tool is also shown which permits a two-stage cementing operation to be performed with only one run down the hole.
A drill pipe actuable stage collar for cementing a well casing in a bore hole comprising a stage collar case adapted to be placed in the well casing at a predeterminable location, said stage collar case including a plurality of ports communicating with an annulus around the well casing, closing sleeve means for opening and closing said stage collar ports, said closing sleeve means being adapted to slidably move from an initial closed position to an open position and to a closed position with respect to said stage collar ports, means for shifting said closing sleeve means from said initial closed position to the open position and subsequently to a closed position, said shifting means being operable by drill pipe movement, and means operably associated with said shifting means and closing sleeve means for locking said closing sleeve means in said closed position, said closing sleeve means, stage collar case and locking means providing a substantially uniform inner diameter bore of the stage collar which does not have to be drilled out after the stage collar is closed.
Dependencies are inferred from the claim text.