Lead Impression
Impression block, also known as lead impression, is a deforming tool used to acquire the preparation depth of fish, the shape of fish top and to check the inner diameter of casing.Under compress pressure from drilling string,the relatively soft lead material on the bottom of impression block will deform after pressing on the fish.
Impression block consists of sub and lead block.There are circulating water holes in the center of the lead block and there is annular groove on the sub to fix the lead block.
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Imprint Description |
Fault Diagnosis |
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Fish |
Rod |
Clear imprint on the center |
Fish is upright,use die collar or overshot |
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Oblique edge on the rim |
Fish tilted,use fishing tools with guide shoe or stabilizing function. |
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Transverse semicircle imprint |
Fish laying horizontally,use pulling out shoes |
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Pipe |
Single circle imprint on the center |
Pin end fish top,upright,use die collar or overshot |
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Single circle imprint with breach |
Pin end fish top,but with break thread,Pay attention to protecting fish top while fishing |
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Single circle imprint on the side |
Fish tilted,use fishing tools with guide shoe or stabilizing function. |
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Double circle imprint on the center |
Box end fish top,upright,use taper tap or fishing spear |
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Double circle imprint on the side |
Fish tilted,use fishing tools with guide shoe or stabilizing function. |
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Wire |
Rope type imprint on the bottom |
Wire on the well bottom,use wire hook |
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Rope type imprint on the flank |
Wire sticks on the well wall,use wire hook |
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Straight rod circle imprint on the bottom |
Electric cable,use wire hook |
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Small item |
Scattered small imprints |
Use fishing tools for small fish |
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Other |
Sand imprint on the bottom |
Fish buried by sand,use fishing tools with flushing function or doing sand washing first |
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Sinking on the center,the edge is blunt without sharp angle |
The drilling fluid pierced the impression block, and failed to encounter any fish. |
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