| 1 | D.J.F. Services, Inc. | Holdenville, OK 74848 | Oil & Gas Operator | Oct 2025 |
| 2 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 3 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 4 | Dantex Oil & Gas, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Aug 2003 |
| 5 | Daubert Operating, L.L.C. | San Antonio, TX 78209 | Oil Operator | Oct 2025 |
| 6 | Dawsey Operating Company | Georgetown, TX 78628 | Oil & Gas Operator | Mar 2016 |
| 7 | Dee-Jay Exploration Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Oct 2025 |
| 8 | Del Petroleum Corporation | Dallas, TX 75219 | Oil & Gas Operator | Jan 2012 |
| 9 | Delcar, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 1995 |
| 10 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 11 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 12 | Diamond Energy Services, LP | Tulsa, OK 74103 | Oil Operator | Oct 2025 |
| 13 | Digital Operating Company LLC | Boerne, TX 78006 | Oil & Gas Operator | Oct 2025 |
| 14 | Discovery Petroleum, L.L.C. | Alice, TX 78333 | 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 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 18 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 19 | Downing Well Service, Inc. | Devine, TX 78016 | Oil & Gas Operator | Oct 2025 |
| 20 | Driscoll S.W.D. Inc. | San Antonio, TX 78229 | Oil & Gas Operator | Oct 2025 |
| 21 | Durst Oil Company | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Sep 2000 |
| 22 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |