Importance

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Abstract

A cementing system using a tubular member 43 coupled to a string of tubing 14 where upper and lower tubular liner wiper plugs (20, 21) are independently attached to and separately releasable from the tubular member. The upper tubular liner wiper plug 20 has outer liner wiper seal members, an outer latching mechanism (95) and an inner latching mechanism (52). A fluid bypass (59) is located in the liner wiper plug (20) below the wiper seal members with a check valve structure for bypassing fluid from below the seal members to the bore (45) of the tubular member in response to a pressure differential. A second check valve structure (46) is provided in the tubular member to provide a fluid bypass from the exterior of the tubular member above the seal members to the interior of the tubular member in response to a pressure differential. The lower tubular liner wiper plug (21) is provided with upper, internal spring latch fingers (71) for releasable attachment to the tubular member and an internal, releasable valve sleeve 90 in a bore 89 and a valve opening 85 in a tubular depending section of the wiper plug. A pump down plug member 100 locks into the releasable valve sleeve 90 above the valve opening 85 to form a lower plug assembly. When the lower plug assembly reaches a lower landing collar, the releasable valve sleeve 90 is released by pressure and moves to open the valve opening 85 to permit cement slurry to pass through the valve opening 85 to the float shoe and through to the annulus of the well bore and the liner.

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First Claim