| 1 | Dahco Operating, LLC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 2 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 3 | Dartex Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | Oct 2025 |
| 4 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Oct 2025 |
| 5 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 6 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 7 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 8 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 9 | Dinero Oil Corporation | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Nov 1999 |
| 10 | Dirks Petroleum Company | Beeville, TX 78104 | Oil & Gas Operator | Oct 2025 |
| 11 | Dirks, R. W. | Tuleta, TX 78162 | Oil & Gas Operator | May 1999 |
| 12 | Dirnett, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Oct 2025 |
| 13 | Discovery Energy Corp. CC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 14 | Discovery Petroleum, L.L.C. | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 15 | DML Exploration, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 16 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 17 | Dominion Minerals Corporation | Houston, TX 77014 | Oil & Gas Operator | Nov 2009 |
| 18 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 19 | Donna-Lynne Oil Co. | George West, TX 78022 | Oil & Gas Operator | Jun 2018 |
| 20 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 21 | Double Play Oil & Gas | Portland, TX 78374 | Oil & Gas Operator | Dec 2001 |
| 22 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 23 | Dougherty Properties | Beeville, TX 78104 | Oil & Gas Operator | Jun 1997 |
| 24 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 25 | Drillers Energy Search, Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 1996 |
| 26 | DRS Exploration Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 1999 |
| 27 | Durango Resources Corp. | Houston, TX 77043 | Oil & Gas Operator | Oct 2025 |
| 28 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |