CPC Main Group
E21B 27/00 Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits
3 direct subcodes
Child Classifications
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- E21B 27/02 Dump bailers, i.e. containers for depositing substances, e.g. cement or acids
- E21B 27/04 where the collecting or depositing means include helical conveying means
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