| 摘要 |
SINGLE PLUG ARRANGEMENT, LOCK THEREFOR AND METHOD OF USE A single wiper (10) is releasably and sealably positioned adjacent the lower end an operating string (not shown) and locked therewith to prevent premature release from the operating string upon manipulation of the operating string. The sealing relationship between the wiper (10) and the operating string prevents communication of operating string pressure from the operating string to the external resilient ribs (12) of the wiper adjacent the position of the wiper on the operating string. When a pump down plug (45) is sealably seated within the bore (11) of the wiper (45), fluid pressure is confined to act on a piston (P) between the operating string and the wiper (45) to unlock the wiper (45) from the operating string so that it may be released therefrom.
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