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PCE
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CPC Subgroup
E21B 21/12

using drilling pipes with plural fluid passages, e.g. closed circulation systems

Full Title

Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (freeing objects stuck in boreholes by flushing E21B31/03) > using drilling pipes with plural fluid passages, e.g. closed circulation systems

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