E21B 21/00
Methods or apparatus for flushing boreholes
Official 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)
E21B21/00 (Methods or apparatus for flushing boreholes) appears on 7,389 US grants and 6,735 published applications in this corpus.
Search patents in E21B- Granted patents
- 7,389
- Published applications
- 6,735
- Assignees
- 1,995
- Inventors
- 10,426
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 65 | 0 |
| 1977 | 40 | 0 |
| 1978 | 57 | 0 |
| 1979 | 34 | 0 |
| 1980 | 48 | 0 |
| 1981 | 89 | 0 |
| 1982 | 64 | 0 |
| 1983 | 67 | 0 |
| 1984 | 84 | 0 |
| 1985 | 68 | 0 |
| 1986 | 70 | 0 |
| 1987 | 72 | 0 |
| 1988 | 50 | 0 |
| 1989 | 74 | 0 |
| 1990 | 53 | 0 |
| 1991 | 53 | 0 |
| 1992 | 55 | 0 |
| 1993 | 55 | 0 |
| 1994 | 54 | 0 |
| 1995 | 47 | 0 |
| 1996 | 48 | 0 |
| 1997 | 29 | 0 |
| 1998 | 64 | 0 |
| 1999 | 71 | 0 |
| 2000 | 88 | 0 |
| 2001 | 117 | 31 |
| 2002 | 106 | 90 |
| 2003 | 95 | 115 |
| 2004 | 101 | 168 |
| 2005 | 80 | 114 |
| 2006 | 112 | 159 |
| 2007 | 115 | 171 |
| 2008 | 112 | 175 |
| 2009 | 100 | 181 |
| 2010 | 148 | 194 |
| 2011 | 125 | 204 |
| 2012 | 143 | 222 |
| 2013 | 163 | 287 |
| 2014 | 223 | 344 |
| 2015 | 213 | 338 |
| 2016 | 277 | 390 |
| 2017 | 267 | 439 |
| 2018 | 340 | 419 |
| 2019 | 433 | 425 |
| 2020 | 457 | 459 |
| 2021 | 482 | 431 |
| 2022 | 415 | 324 |
| 2023 | 416 | 346 |
| 2024 | 357 | 306 |
| 2025 | 300 | 239 |
| 2026 | 193 | 164 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Subgroups
Granted patents
- E21B 21/06Arrangements for treating drilling fluids outside the borehole2,174
- E21B 21/10Valve arrangements in drilling-fluid circulation systems1,989
- E21B 21/08Controlling or monitoring pressure or flow of drilling fluid1,721
- E21B 21/003Means for stopping loss of drilling fluid874
- E21B 21/01Arrangements for handling drilling fluids or cuttings outside the borehole711
- E21B 21/12Methods or apparatus for flushing boreholes: using drilling pipes with plural fluid386
- E21B 21/001Methods or apparatus for flushing boreholes: specially adapted for underwater drilling328
- E21B 21/002Down-hole drilling fluid separation systems211
All 12 subgroupsShow fewer
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Most cited
By later US patents
- Method for continuously mixing fluids517US 5,426,137 AHalliburton Company · 1995
- Drilling systems with sensors for determining properties of drilling fluid downhole402US 6,176,323 B1Baker Hughes Incorporated · 2001
- Coalbed methane drilling359US 5,411,104 AConoco Inc. · 1995
- Downhole surge pressure reduction system and method of use340US 5,960,881 AJerry P. Allamon · 1999
- Systems and methods for routing pressurized fluid305US 8,905,056 B2Halliburton Energy Services.Inc. · 2014