| 1 | D. G. Oil Co. | Dennis, TX 76439 | Oil & Gas Operator | Oct 2025 |
| 2 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 3 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 4 | Dallas Petroleum Group, LLC | Dallas, TX 75379 | Oil & Gas Operator | Oct 2025 |
| 5 | Davis Petroleum Corp. | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 6 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 7 | Deguello Operating LLC | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 8 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 9 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 10 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 11 | Devon Energy Operating Co., L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2009 |
| 12 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 13 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 14 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 15 | Digital Operating Company LLC | Boerne, TX 78006 | Oil & Gas Operator | Oct 2025 |
| 16 | Dimock Operating Company | Frisco, TX 75034 | Oil & Gas Operator | Oct 2025 |
| 17 | Dinero Oil Corporation | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Nov 1999 |
| 18 | Discorbis Oil Company | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2019 |
| 19 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 20 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 21 | Dorado Drilling, Inc. | Gulfport, MS 39501 | Oil & Gas Operator | Oct 2025 |
| 22 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 23 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 24 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |