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CPC Subgroup
E21B 33/068

having provision for introducing objects or fluids into, or removing objects from, wells (cementing-heads E21B33/05)

Full Title

Sealing or packing boreholes or wells > Surface sealing or packing > Well heads; Setting-up thereof > having provision for introducing objects or fluids into, or removing objects from, wells (cementing-heads E21B33/05)

2 direct subcodes

Child Classifications

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  • E21B 33/072 for cable-operated tools (E21B33/076 takes precedence)
  • E21B 33/076 specially adapted for underwater installations

Top Applicants

Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT

  1. HALLIBURTON ENERGY SERVICES GROUP US 27,652
  2. SAUDI ARABIAN OIL COMPANY SA 7,755
  3. PETROCHINA COMPANY 7,025
  4. BAKER HUGHES US 6,589
  5. SCHLUMBERGER TECHNOLOGY US 6,151
  6. SINOPEC (CHINA PETROCHEMICAL CORPORATION) 4,443
  7. SCHLUMBERGER TECHNOLOGY NL 4,255
  8. CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 3,991
  9. SERVICES PETROLIERS SCHLUMBERGER FR 3,300
  10. SCHLUMBERGER CANADA CA 3,086