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Dropped BHA may induce formation breakdown from pressure surge

Journal Article · · Oil and Gas Journal
OSTI ID:37583
A calculation method helps determine the dynamic gradient when a parted drillstring falls to the bottom of a well, possibly inducing formation breakdown. When a drillstring parts above a critical depth, dropping the bottom hole assembly (BHA), formation breakdown can occur from the falling fish. The equations help determine a critical drop velocity, which indicates if the BHA may undergo plastic deformation as it hits bottom. Understanding the critical drop velocity and critical depth for a dropping fish could help better prepare drilling crews during fishing operations and possible well control operations should other problems develop. The paper describes the analytical model and the assumptions used in its development, and illustrates its use with an example.
OSTI ID:
37583
Journal Information:
Oil and Gas Journal, Journal Name: Oil and Gas Journal Journal Issue: 17 Vol. 93; ISSN OIGJAV; ISSN 0030-1388
Country of Publication:
United States
Language:
English

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