| 摘要 |
A method is disclosed using an overshot retrieving device which is lowered into a borehole by means of tubing until the overshot arrives at a lost tool. An attempt is made to engage the tool with the overshot and after the attempt the overshot is raised a predetermined distance. An acoustical well sounder provides a soundwave in the tubing. When the overshot has successfully engaged the lost tool, the recorder of the well sounder provides a recording having a primary deflection in one sense in response to a reflection of the soundwave to indicate that the tool has been engaged. When the overshot has not engaged the tool, the reflection of the soundwave causes the recording to have a primary deflection in an opposite sense to indicate that the tool has not been engaged. An operator may then remove the overshot, the lost tool and tubing or repeat the engagement operation in accordance with the record provided by the recorder.
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