CPC Main Group
E21B 25/00 Apparatus for obtaining or removing undisturbed cores, e.g. core barrels or core extractors (core bits E21B10/02)
7 direct subcodes
Child Classifications
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- E21B 25/02 the core receiver being insertable into, or removable from, the borehole without withdrawing the drilling pipe
- E21B 25/06 the core receiver having a flexible liner or inflatable retaining means
- E21B 25/08 Coating, freezing, consolidating cores (E21B25/06 takes precedence); Recovering uncontaminated cores or cores at formation pressure
- E21B 25/10 Formed core retaining or severing means (E21B25/06, E21B25/08 take precedence)
- E21B 25/16 for obtaining oriented cores
- E21B 25/18 the core receiver being specially adapted for operation under water
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