| 摘要 |
The invention relates to a receiver for use in an oil well during a cementing step, to receive a plug which seals off the cement from the interior of the well while the cement hardens. The receiver has a flow limiting flap which restricts the amount of drilling mud which can flow into the well casing while the casing is lowered into the well. The mating plug for the receiver has latches which engage the bottom of the receiver so that the plug cannot be dislodged upwardly.
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