E21B 21/085
Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure
Official title: {Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure}
E21B21/085 (Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure) appears on 331 US grants and 335 published applications in this corpus.
Search patents in E21B- Granted patents
- 331
- Published applications
- 335
- Assignees
- 115
- Inventors
- 545
- Latest grant
- 26 May 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1977 | 1 | 0 |
| 1978 | 0 | 0 |
| 1979 | 0 | 0 |
| 1980 | 1 | 0 |
| 1981 | 0 | 0 |
| 1982 | 0 | 0 |
| 1983 | 0 | 0 |
| 1984 | 0 | 0 |
| 1985 | 2 | 0 |
| 1986 | 1 | 0 |
| 1987 | 0 | 0 |
| 1988 | 1 | 0 |
| 1989 | 0 | 0 |
| 1990 | 0 | 0 |
| 1991 | 1 | 0 |
| 1992 | 0 | 0 |
| 1993 | 2 | 0 |
| 1994 | 3 | 0 |
| 1995 | 0 | 0 |
| 1996 | 0 | 0 |
| 1997 | 0 | 0 |
| 1998 | 2 | 0 |
| 1999 | 5 | 0 |
| 2000 | 8 | 0 |
| 2001 | 9 | 4 |
| 2002 | 7 | 12 |
| 2003 | 12 | 22 |
| 2004 | 11 | 41 |
| 2005 | 25 | 21 |
| 2006 | 19 | 23 |
| 2007 | 33 | 16 |
| 2008 | 11 | 17 |
| 2009 | 8 | 16 |
| 2010 | 15 | 10 |
| 2011 | 11 | 15 |
| 2012 | 13 | 9 |
| 2013 | 15 | 14 |
| 2014 | 14 | 14 |
| 2015 | 9 | 11 |
| 2016 | 10 | 16 |
| 2017 | 10 | 10 |
| 2018 | 10 | 10 |
| 2019 | 11 | 6 |
| 2020 | 9 | 12 |
| 2021 | 12 | 9 |
| 2022 | 11 | 7 |
| 2023 | 7 | 6 |
| 2024 | 7 | 4 |
| 2025 | 4 | 4 |
| 2026 | 1 | 6 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Recent patents
- Reverse circulation jet pump and reaming stabilizer26 May 2026US 12,637,914 B2
- Method of underbalanced drilling using foaming agent30 Dec 2025US 12,509,952 B2King Fahd University of Petroleum and Minerals
- Riser-less managed pressure operations11 Nov 2025US 12,467,330 B2Weatherford Technology Holdings, LLC
- Stimulating wells created by underbalanced coiled tubing drilling22 Apr 2025US 12,281,554 B2Saudi Arabian Oil Company
- Completing a wellbore15 Apr 2025US 12,276,182 B2Saudi Arabian Oil Company
- Characterizing Gases in Wellbores10 Sep 2026US 2026/0266149 A1Saudi Arabian Oil Company
- Laser Induced Breakdown Spectroscopy of Drilling Cuttings10 Sep 2026US 2026/0266731 A1Saudi Arabian Oil Company
- Reverse Circulation Jet Pump and Reaming Stabilizer30 Apr 2026US 2026/0117611 A1
- Real-time well productivity index optimization in underbalanced drilling23 Apr 2026US 2026/0110227 A1Schlumberger Technology Corporation
- Coiled tubing drilling advisor5 Mar 2026US 2026/0063023 A1Schlumberger Technology Corporation
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
- Two string drilling system using coil tubing164US 6,854,534 B22005
- Rotating subsea diverter162US 6,230,824 B1Hydril Company · 2001