CPC Main Group
E21B 37/00 Methods or apparatus for cleaning boreholes or wells (E21B21/00 takes precedence)
4 direct subcodes
Child Classifications
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- E21B 37/02 Scrapers specially adapted therefor
- E21B 37/06 using chemical means for preventing or limiting the deposition of paraffins or like substances
- E21B 37/08 cleaning in situ of down-hole filters, screens, or gravel packs (E21B37/06 takes precedence)
- E21B 37/10 Well swabs
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