Lifting-lowering And Releasing Overshot
Lifting-Lower and releasing overshot is a fish tool in the casing which fishes fractured tubing and drill string. If fish drill string is stuck heavily and hard to complete fishing work, while need to release fish, may get back the tool by bumping drill string down and lift directly.
The product is excellent for fishing operations as it does not require rotation. Fishes can be caught or released through simple lifting or lowering of the tool.
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Structure
Lifting-Lower and Releasing Overshot is composes of top sub, bowl, guide pin, guide sleeve, joint sleeve, plug, roller pin, slip, guide, as shown in the figure. The box thread of top sub is connected with drill stem and the pin thread is connected with the bowl, The bottom of bowl is connected to the guide. An inner cone in the bowl matches the slip. Box thread of guide sleeve is connected with joint sleeve, track trenches are milled on another outer surface: three long trenches and three short trenches act as guiding and reversing. When guide pin locates in long trench is in the condition of fish. When guide pin locates in short trench is in the condition of release. Joint sleeve is two petals formation. It makes slip and guide sleeve connection and by roller pin act as bearing. The inner surface of slip has fish thread, guide is on the bottom and can make fish introduce into slip successfully.
Working Principle
The tool complete fishing and releasing fish through long, short track trenches. When the tool reaches the top of fish, it is lowered and is in contact with the fish. Through lifting and lowering, guide pin is in the position of long or short trench, slip is in the situation of fishing or releasing, in the condition of non-rotating complete fishing and releasing fish.
