| 1 | D-O-R Lease Service, Inc. | | Oil & Gas Operator | Mar 2009 |
| 2 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 3 | Daniel Oil Company | | Oil & Gas Operator | Jan 1983 |
| 4 | Dantex Oil & Gas, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Aug 2003 |
| 5 | Darsey Operating Corporation | | Oil & Gas Operator | Sep 1990 |
| 6 | Davis Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 1988 |
| 7 | Davis Petroleum Corp. | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 8 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Dec 2025 |
| 9 | DBL DRLG.&Prod. Services, Inc. | | Oil & Gas Operator | Jul 1997 |
| 10 | Dean Enterprises, Inc. | | Oil & Gas Operator | Jun 2019 |
| 11 | Delta Energy Resources, Inc. | | Oil & Gas Operator | Jun 1990 |
| 12 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Dec 2025 |
| 13 | Denbury Resources Inc. | Plano, TX 75024 | Oil & Gas Operator | Dec 2003 |
| 14 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 15 | Dew Oil And Gas Co.,Inc. | | Oil & Gas Operator | Dec 1989 |
| 16 | Di Energy Inc. | Houston, TX 77067 | Oil & Gas Operator | Jan 2004 |
| 17 | Diamex Company | | Oil & Gas Operator | Oct 1982 |
| 18 | Diamond Shamrock Expl. Co. | | Oil & Gas Operator | Jun 1987 |
| 19 | Dome De Sel LLC | | Oil & Gas Operator | Nov 2024 |
| 20 | Dragon Energy Corporation | | Oil & Gas Operator | Oct 2006 |
| 21 | Drew Cornell, Inc. | | Oil & Gas Operator | Jun 1992 |
| 22 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 23 | Dynamic Exploration, Inc. | | Oil & Gas Operator | Oct 2003 |
| 24 | Dynamic Offshore Resources, LLC | Houston, TX 77042 | Oil & Gas Operator | Dec 2025 |