| 1 | D-Mil Production Inc | Argyle, TX 76226 | Oil & Gas Operator | Jun 2026 |
| 2 | Dalen Resources Oil & Gas Co | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 3 | Dallas Petroleum Group, LLC | Dallas, TX 75379 | Oil & Gas Operator | Jun 2026 |
| 4 | Dartex Energy Corporation | Austin, TX 78731 | Oil & Gas Operator | Jun 2026 |
| 5 | Davis Gulf Coast, Inc. | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2026 |
| 6 | DCM Resources, LLC | Humble, TX 77346 | Oil Operator | Jun 2026 |
| 7 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | Mar 2026 |
| 8 | Decker Operating Co., L.L.C. | Houston, TX 77008 | Oil & Gas Operator | Jun 2026 |
| 9 | Delco Operating Company LP | Houston, TX 77056 | Oil & Gas Operator | May 2020 |
| 10 | Denali Oil & Gas Management LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 11 | Dewbre Petroleum Corporation | Corpus Christ, TX 78404 | Oil & Gas Operator | Jun 2026 |
| 12 | Dillon, H. L., Jr. | Houston, TX 77027 | Oil & Gas Operator | Mar 1996 |
| 13 | Dinero Oil Corporation | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Nov 1999 |
| 14 | Discovery Energy Corp. CC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Jun 2026 |
| 15 | DJ Exploration, Inc. | San Antonio, TX 78257 | Oil & Gas Operator | Jun 2026 |
| 16 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 17 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 18 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | Jun 2026 |
| 19 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Jun 2026 |
| 20 | Double S Operating Co. | Wichita Falls, TX 76308 | Oil & Gas Operator | Jun 2026 |
| 21 | Drachen Oil Company | San Antonio, TX 78258 | Oil & Gas Operator | Jun 2026 |
| 22 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 23 | Drillmar Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | Nov 2014 |
| 24 | Drillmar Operating Company | Houston, TX 77019 | Oil & Gas Operator | Jun 2013 |
| 25 | Driscoll S.W.D. Inc. | San Antonio, TX 78229 | Oil & Gas Operator | Jun 2026 |
| 26 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |
| 27 | Dune Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Jun 2016 |