CPC Subgroup
E21B 47/02 Determining slope or direction
Full Title
Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) > Determining slope or direction
3 direct subcodes
Child Classifications
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- E21B 47/022 of the borehole, e.g. using geomagnetism
- E21B 47/024 of devices in the borehole (determining slope or direction of the borehole E21B47/022)
- E21B 47/026 of penetrated ground layers
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