E21B 4/20
Combined with surface drive
Official title: combined with surface drive (E21B4/10 takes precedence)
E21B4/20 (Combined with surface drive) appears on 100 US grants and 34 published applications in this corpus.
Search patents in E21B- Granted patents
- 100
- Published applications
- 34
- Assignees
- 55
- Inventors
- 160
- Latest grant
- 14 Apr 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 5 | 0 |
| 1977 | 3 | 0 |
| 1978 | 1 | 0 |
| 1979 | 3 | 0 |
| 1980 | 4 | 0 |
| 1981 | 7 | 0 |
| 1982 | 3 | 0 |
| 1983 | 2 | 0 |
| 1984 | 3 | 0 |
| 1985 | 2 | 0 |
| 1986 | 2 | 0 |
| 1987 | 4 | 0 |
| 1988 | 1 | 0 |
| 1989 | 5 | 0 |
| 1990 | 0 | 0 |
| 1991 | 2 | 0 |
| 1992 | 2 | 0 |
| 1993 | 3 | 0 |
| 1994 | 2 | 0 |
| 1995 | 1 | 0 |
| 1996 | 0 | 0 |
| 1997 | 4 | 0 |
| 1998 | 3 | 0 |
| 1999 | 1 | 0 |
| 2000 | 3 | 0 |
| 2001 | 2 | 1 |
| 2002 | 5 | 4 |
| 2003 | 3 | 1 |
| 2004 | 1 | 2 |
| 2005 | 2 | 4 |
| 2006 | 4 | 1 |
| 2007 | 1 | 2 |
| 2008 | 1 | 0 |
| 2009 | 0 | 0 |
| 2010 | 0 | 0 |
| 2011 | 0 | 0 |
| 2012 | 0 | 0 |
| 2013 | 0 | 0 |
| 2014 | 0 | 3 |
| 2015 | 0 | 1 |
| 2016 | 0 | 2 |
| 2017 | 1 | 1 |
| 2018 | 3 | 3 |
| 2019 | 2 | 0 |
| 2020 | 1 | 3 |
| 2021 | 1 | 2 |
| 2022 | 4 | 1 |
| 2023 | 1 | 1 |
| 2024 | 1 | 0 |
| 2025 | 0 | 2 |
| 2026 | 1 | 0 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
- Drilling assembly14 Apr 2026US 12,601,223 B2BAUER Spezialtiefbau GmbH
- Hydraulically driven rotating string reamer and methods20 Feb 2024US 11,905,794 B2Saudi Arabian Oil Company
- Active alternator control in a downhole tool string9 May 2023US 11,643,909 B2Schlumberger Technology Corporation
- Method and apparatus for percussion drilling20 Sep 2022US 11,448,013 B2Epiroc Drilling Solutions, LLC
- Downhole disconnect tool17 May 2022US 11,332,983 B2Thru Tubing Solutions, Inc.
- Systems and methods for downhole communication4 Dec 2025US 2025/0369349 A1Schlumberger Technology Corporation
- Drilling assembly6 Nov 2025US 2025/0341132 A1BAUER Spezialtiefbau GmbH
- Hydraulically driven rotating string reamer and methods16 Nov 2023US 2023/0366270 A1Saudi Arabian Oil Company
- High speed drilling system and methods of using same5 May 2022US 2022/0136329 A1Bly IP Inc.
- Active alternator control in a downhole tool string12 Aug 2021US 2021/0246765 A1Schlumberger Technology Corporation
Most cited
By later US patents
- Actively controlled rotary steerable system and method for drilling wells344US 6,092,610 ASchlumberger Technology Corporation · 2000
- Device for removal of intraluminal occlusions220US 5,350,390 A1994
- Directional drilling apparatus and method164US 5,113,953 A1992
- Simultaneous drilling and casing device159US 4,842,081 ASociete Nationale Elf Aquitaine (Production) · 1989
- System for directional drilling and related method of use157US 4,854,397 AAmoco Corporation · 1989