CPC Main Group
E21B 41/00 Equipment or details not covered by groups E21B15/00 - E21B40/00
12 direct subcodes
Child Classifications
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- E21B 41/02 in situ inhibition of corrosion in boreholes or wells
- E21B 41/04 Manipulators for underwater operations, e.g. temporarily connected to well heads
- E21B 41/06 Work chambers for underwater operations, e.g. temporarily connected to well heads
- E21B 41/08 Underwater guide bases, e.g. drilling templates; Levelling thereof
- E21B 41/10 Guide posts, e.g. releasable; Attaching guide lines to underwater guide bases
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