E21B 21/12
Methods or apparatus for flushing boreholes: using drilling pipes with plural fluid
Official title: using drilling pipes with plural fluid passages, e.g. closed circulation systems
E21B21/12 (Methods or apparatus for flushing boreholes: using drilling pipes with plural fluid) appears on 386 US grants and 230 published applications in this corpus.
Search patents in E21B- Granted patents
- 386
- Published applications
- 230
- Assignees
- 191
- Inventors
- 607
- Latest grant
- 25 Aug 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 12 | 0 |
| 1977 | 4 | 0 |
| 1978 | 10 | 0 |
| 1979 | 5 | 0 |
| 1980 | 6 | 0 |
| 1981 | 11 | 0 |
| 1982 | 10 | 0 |
| 1983 | 3 | 0 |
| 1984 | 4 | 0 |
| 1985 | 8 | 0 |
| 1986 | 7 | 0 |
| 1987 | 15 | 0 |
| 1988 | 9 | 0 |
| 1989 | 11 | 0 |
| 1990 | 8 | 0 |
| 1991 | 6 | 0 |
| 1992 | 8 | 0 |
| 1993 | 9 | 0 |
| 1994 | 7 | 0 |
| 1995 | 4 | 0 |
| 1996 | 7 | 0 |
| 1997 | 3 | 0 |
| 1998 | 1 | 0 |
| 1999 | 0 | 0 |
| 2000 | 5 | 0 |
| 2001 | 7 | 1 |
| 2002 | 7 | 3 |
| 2003 | 2 | 10 |
| 2004 | 5 | 10 |
| 2005 | 7 | 7 |
| 2006 | 6 | 3 |
| 2007 | 5 | 1 |
| 2008 | 3 | 5 |
| 2009 | 2 | 14 |
| 2010 | 3 | 13 |
| 2011 | 8 | 8 |
| 2012 | 9 | 13 |
| 2013 | 8 | 18 |
| 2014 | 13 | 7 |
| 2015 | 11 | 15 |
| 2016 | 12 | 9 |
| 2017 | 7 | 11 |
| 2018 | 12 | 10 |
| 2019 | 17 | 12 |
| 2020 | 10 | 19 |
| 2021 | 20 | 13 |
| 2022 | 12 | 5 |
| 2023 | 9 | 7 |
| 2024 | 8 | 9 |
| 2025 | 6 | 5 |
| 2026 | 4 | 2 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
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- Method and apparatus for removing debris from a drill hole during drilling1 Jul 2025US 12,345,106 B2
- Drilling robot with an extrusion unit10 Sep 2026US 2026/0266139 A1ZHAW - Zürcher Hochschule Für Angewandte Wissenschaften
- Composite umbilical for pulse power boring system16 Jul 2026US 2026/0201753 A1Halliburton Energy Services.Inc.
- Pulsed power drilling with multiple selective drilling fluids7 Aug 2025US 2025/0250863 A1Halliburton Energy Services.Inc.
- Drill string and components therefor17 Jul 2025US 2025/0230721 A1Tri-Tube Drilling Systems Pty Ltd
- Coal mining system and method of dual circulation drilling with mechanical reaming and abrasive jet29 May 2025US 2025/0172062 A1China University of Mining and Technology, Beijing
Most cited
By later US patents
- Method and system for drilling and completing underbalanced multilateral wells utilizing a dual string technique in a live well205US 6,065,550 A2000
- Underbalance jet pump drilling method189US 5,355,967 AUnion Oil Company of California · 1994
- Method and system for drilling underbalanced radial wells utilizing a dual string technique in a live well170US 5,720,356 A1998
- Reverse circulation bit apparatus165US 4,823,890 ALongyear Company · 1989
- Two string drilling system using coil tubing164US 6,854,534 B22005