Lead Impression Block In Oil & Gas
The Lead Impression Block in oil and gas is designed to give an imprint of the top of a fish in the hole to help determine the condition and position of the top of the fish. The Impression Block can also be used to give clues on how to retrieve an unknown fish in the well, and used in wireline fishing operations to identify obstructions. It is also can be run to get the dimensions of the casing collapse zones.
https://www.drillingmanual.com/lead-impression-block-oil-gas/