CPC Subgroup
E21B 25/10 Formed core retaining or severing means (E21B25/06, E21B25/08 take precedence)
Full Title
Apparatus for obtaining or removing undisturbed cores, e.g. core barrels or core extractors (core bits E21B10/02) > Formed core retaining or severing means (E21B25/06, E21B25/08 take precedence)
2 direct subcodes
Child Classifications
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- E21B 25/12 of the sliding wedge type
- E21B 25/14 mounted on pivot transverse to core axis
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 27,652
- SAUDI ARABIAN OIL COMPANY SA 7,755
- PETROCHINA COMPANY 7,025
- BAKER HUGHES US 6,589
- SCHLUMBERGER TECHNOLOGY US 6,151
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 4,443
- SCHLUMBERGER TECHNOLOGY NL 4,255
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 3,991
- SERVICES PETROLIERS SCHLUMBERGER FR 3,300
- SCHLUMBERGER CANADA CA 3,086