| 1 | D. G. Oil Co. | Dennis, TX 76439 | Oil & Gas Operator | Dec 2025 |
| 2 | Daniels Corporation, The | Seabrook, TX 77586 | Oil & Gas Operator | Dec 2025 |
| 3 | Dartex Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | Dec 2025 |
| 4 | Davis Bros. Oil Producers, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2020 |
| 5 | Davis Petroleum Corp. | Houston, TX 77027 | Oil & Gas Operator | Dec 2025 |
| 6 | Daystar Operating Company, LLC | Austin, TX 78750 | Oil & Gas Operator | Apr 2008 |
| 7 | Delaware Davis Petroleum Corp. | Houston, TX 77056 | Oil & Gas Operator | Jan 2000 |
| 8 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Dec 2025 |
| 9 | Devon Energy Operating Co., L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2009 |
| 10 | Devon Energy Production Company, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 11 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 12 | Doggy Oil Corp | Decatur, GA 30031 | Oil & Gas Operator | Dec 2025 |
| 13 | Drillmar Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | Nov 2014 |
| 14 | Dune Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Jun 2016 |
| 15 | Dynamic Of Texas, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Aug 2003 |
| 16 | Dynamic Production, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2025 |