| 摘要 |
A plug-dropping head is disclosed in which the objects to be dropped are placed in individual discrete passages. A motor-driven or hand-operated rotating member orients an entrance to a passage going through it to, in series, individual passages in the housing for sequential dropping of objects downhole. A relief port is provided so that as the rotating outlet member moves from one passage in the housing to the next, the relief passage prevents deadheading of the surface pump.
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