| 1 | D & V Petroleum Corporation | | Oil & Gas Operator | May 1992 |
| 2 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 3 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 4 | Darsey Operating Corporation | | Oil & Gas Operator | Sep 1990 |
| 5 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Oct 2025 |
| 6 | DBL DRLG.&Prod. Services, Inc. | | Oil & Gas Operator | Jul 1997 |
| 7 | Deck Oil Company | Tulsa, OK 74101 | Oil & Gas Operator | Jun 2020 |
| 8 | Desco Oil Company | Houston, TX 77056 | Oil & Gas Operator | Feb 2017 |
| 9 | Despot Production Company | | Oil & Gas Operator | May 1983 |
| 10 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 11 | Di Energy Inc. | Houston, TX 77067 | Oil & Gas Operator | Jan 2004 |
| 12 | Diamond S Operating Co. | | Oil & Gas Operator | Oct 1992 |
| 13 | DLB Oil & Gas, Inc. | Big Lake, TX 76932 | Oil & Gas Operator | Oct 2025 |
| 14 | Dome Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2016 |
| 15 | Donald J. Zadeck | | Oil & Gas Operator | Feb 1998 |
| 16 | Dunn Exploration Company, LLC | | Oil & Gas Operator | Jan 2025 |
| 17 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 18 | Dynamic Exploration, Inc. | | Oil & Gas Operator | Oct 2003 |