IPC Main Group
E21B 25/00 Apparatus for obtaining or removing undisturbed cores, e.g. core barrels or core extractors
Introduced: September 1968
Last revised: January 2006
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
Additional Content
Core bits
Related Keywords
CORE(S) barrels, breakers or extractorsEXTRACTING articles from boreholesSAMPLING in wells and bores
6 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; Recovering uncontaminated cores or cores at formation pressure
- E21B 25/1 Formed core retaining or severing means
- 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 26,607
- PETROCHINA COMPANY 14,382
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
- BAKER HUGHES US 6,269
- SCHLUMBERGER TECHNOLOGY US 5,929
- SAUDI ARABIAN OIL COMPANY SA 5,880
- SOUTHWEST PETROLEUM UNIVERSITY 4,477
- CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
- SCHLUMBERGER TECHNOLOGY NL 4,219