Identifies the first pipeline in which a downhole logging tool is moving during well logging
During the loging the tool starts through tubing which s a first barirer here and when it mopves The downhole tool usually starts well logging through tubing which represents the First Barrier here and when the tool moves below tubing shoe the casing becomes aa First Barrier.
See Also
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Petroleum Industry / Upstream / Subsurface E&P Disciplines / Well & Log Analysis