| 1 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 2 | Dallas Petroleum Group, LLC | Dallas, TX 75379 | Oil & Gas Operator | Oct 2025 |
| 3 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Oct 2025 |
| 4 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 5 | Delaware Ecco Petroleum Inc. | Rockwall, TX 75087 | Oil & Gas Operator | Jul 2001 |
| 6 | Diamond Oil And Gas, Inc. | Kalamazoo, MI 49001 | Oil & Gas Operator | Oct 2025 |
| 7 | Dixie Drilling Company, Inc. | Sherman, TX 75090 | Oil & Gas Operator | Nov 2011 |
| 8 | DKM Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2011 |
| 9 | Dominion Minerals Corporation | Houston, TX 77014 | Oil & Gas Operator | Nov 2009 |
| 10 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 11 | Domino Prod Services Inc | Bellville, TX 77418 | Oil & Gas Operator | Feb 2004 |
| 12 | Douglas Petroleum Inc. | Spring, TX 77379 | Oil & Gas Operator | Nov 2010 |
| 13 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 14 | Durst Oil Company | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Sep 2000 |
| 15 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |
| 16 | Dyson Energy Operating, LLC | Bryan, TX 77802 | Oil & Gas Operator | Jun 2018 |