| 1 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 2 | Dash Production Company, Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Oct 2025 |
| 3 | Davis Asset Management, Inc. | Houston, TX 77010 | Oil & Gas Operator | Dec 2004 |
| 4 | Davis Southern Operating Co LLC | Houston, TX 77004 | Oil & Gas Operator | Oct 2025 |
| 5 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 6 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 7 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 8 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 9 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 10 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 11 | Digital Operating Company LLC | Boerne, TX 78006 | Oil & Gas Operator | Oct 2025 |
| 12 | Dirnett, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Oct 2025 |
| 13 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 14 | Dogwood Operating Company, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 15 | Dolphin Petroleum | Alice, TX 78333 | Oil & Gas Operator | Jun 2008 |
| 16 | Dolphin Petroleum, LP | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 17 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 18 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 19 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 20 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 21 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 22 | Dugger, Glenn | Alice, TX 78332 | Oil & Gas Operator | Nov 2013 |
| 23 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |