E21B 47/18 through the well fluid
Introduced: January 1995
Last revised: January 2012
Full Title
Survey of boreholes or wells > Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling > using acoustic waves > through the well fluid
Classification Context
- Section:
- FIXED CONSTRUCTIONS
- Class:
- EARTH OR ROCK DRILLING; MINING
- Subclass:
- EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
Filing statistics
IPC E21B 47/18 belongs to the parent subclass E21B, which recorded 363,999 patent applications worldwide between 2013 and 2023. Annual filings grew from 30,128 in 2013 to 33,441 in 2023 (+11%), peaking at 39,369 applications in 2020. The most active applicants in class E21 are HALLIBURTON ENERGY SERVICES GROUP (26,607 applications), PETROCHINA COMPANY (14,382 applications) and SINOPEC (CHINA PETROCHEMICAL CORPORATION) (10,137 applications).
Source: EPO PATSTAT, worldwide filings
3 direct subcodes
Child Classifications
Navigate with arrow keys, Enter to open
- E21B 47/2 by modulation of mud waves, e.g. by continuous modulation
- E21B 47/22 by negative mud pulses using a pressure relief valve between drill pipe and annulus
- E21B 47/24 by positive mud pulses using a flow restricting valve within the drill pipe
Top Applicants
Top 10 applicants by patent filingsfor class E21, 2013–2023, worldwide · Source: EPO PATSTAT
- HALLIBURTON ENERGY SERVICES GROUP US 26,607
- PETROCHINA COMPANY 14,382
- SINOPEC (CHINA PETROCHEMICAL CORPORATION) 10,137
- CNPC (CHINA NATIONAL PETROLEUM CORPORATION) 6,517
- BAKER HUGHES US 6,269
- SCHLUMBERGER TECHNOLOGY US 5,929
- SAUDI ARABIAN OIL COMPANY SA 5,880
- SOUTHWEST PETROLEUM UNIVERSITY 4,477
- CHINA UNIVERSITY OF MINING AND TECHNOLOGY 4,357
- SCHLUMBERGER TECHNOLOGY NL 4,219