| 1 | D & V Petroleum Corporation | | Oil & Gas Operator | May 1992 |
| 2 | Dan A. Hughes Company | | Oil & Gas Operator | Dec 2005 |
| 3 | Dan A. Hughes Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Jun 2024 |
| 4 | Daniel Oil Company | | Oil & Gas Operator | Jan 1983 |
| 5 | Darsey Operating Corporation | | Oil & Gas Operator | Sep 1990 |
| 6 | Davis Oil Company | Pawhuska, OK 74056 | Oil & Gas Operator | Jun 2018 |
| 7 | Davis Petroleum Corp. | Houston, TX 77027 | Oil & Gas Operator | Nov 2024 |
| 8 | Davis-Goodman-Medders | | Oil & Gas Operator | Jun 1980 |
| 9 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Nov 2024 |
| 10 | Dean Enterprises, Inc. | | Oil & Gas Operator | Jun 2019 |
| 11 | Deblin Oil & Gas, Inc | | Oil & Gas Operator | Aug 1995 |
| 12 | Denbury Management, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 1999 |
| 13 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Nov 2024 |
| 14 | Denbury Resources Inc. | Plano, TX 75024 | Oil & Gas Operator | Dec 2003 |
| 15 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 16 | Desco Oil Company | Houston, TX 77056 | Oil & Gas Operator | Feb 2017 |
| 17 | Desco-Medders | | Oil & Gas Operator | Jun 1984 |
| 18 | Despot Exploration, Inc. | | Oil & Gas Operator | Apr 1990 |
| 19 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Nov 2024 |
| 20 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 21 | Di Energy Inc. | Houston, TX 77067 | Oil & Gas Operator | Jan 2004 |
| 22 | Diamond Shamrock Expl. Co. | | Oil & Gas Operator | Jun 1987 |
| 23 | Diasu Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 24 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2024 |
| 25 | Dome De Sel LLC | | Oil & Gas Operator | Jun 2024 |
| 26 | Dore-Dyn Production Co., Inc. | | Oil & Gas Operator | Jul 1993 |
| 27 | Duer Wagner & Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1998 |
| 28 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |
| 29 | Dundee Petroleum, Inc. | Buffalo Gap, TX 79508 | Oil & Gas Operator | Aug 2003 |
| 30 | Dune Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Jun 2016 |
| 31 | Dunhill Resources, Inc. | | Oil & Gas Operator | Nov 2005 |
| 32 | Dynamic Exploration PTRS, LLC | | Oil & Gas Operator | Jul 2024 |
| 33 | Dynamic Exploration, Inc. | | Oil & Gas Operator | Oct 2003 |
| 34 | Dynamic Offshore Resources, LLC | Houston, TX 77042 | Oil & Gas Operator | Nov 2024 |