| 摘要 |
The plug-dropping container (2) comprises an elongated housing (10), and a canister (30) disposed co-axially within the housing. The canister (30) is movable from a lower position to an upper position. In its lower position, a fluid bypass area (16) is defined above the canister. When a dart (8) is retained within the canister, fluid is diverted through the bypass (16) and around the canister (30) within an annular area defined between the canister and the housing (10). In one aspect, the canister (30) is moved by rotation of a plug-retaining device (40) below the canister. In its plug-retained position, the plug-retaining device is oriented so that the wall (44) of the plug-retaining device blocks the downward path of the dart (8). In the plug- released position, the plug-retaining device (40) raises the canister (30) t o its upper position, substantially shutting off the bypass (16). A channel (4 5) in the plug-retaining device is thus aligned with a channel (35) in the canister for receiving the plug, and for release into the wellbore (18).</SD OAB>
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