| 摘要 |
The circulation tool 10 for use downhole in a well includes a housing 22 having one or more bypass ports 52 for circulation between a bore 33 in the housing and an annulus surrounding the housing. Sleeve 50 is axially movable within the housing, and axially spaced seals 36, 56 seal between the sleeve and the housing when the sleeve is in the closed position. A flapper 84 is pivotally mounted to the sleeve, and includes a seat about a central bore 85 in the flapper for engagement with the plug. A stop 40 prevents pivoting of the flapper to an open position until the sleeve has moved axially and the seals seal between the sleeve and the housing.
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