| 1 | D & G Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | Dec 1995 |
| 2 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 3 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 4 | Davis Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 1988 |
| 5 | Davis Oil Company-Cox | | Oil & Gas Operator | Aug 1980 |
| 6 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | Oct 2025 |
| 7 | Deblin Oil & Gas, Inc | | Oil & Gas Operator | Aug 1995 |
| 8 | Delta Development Co. Inc. | | Oil & Gas Operator | Dec 1988 |
| 9 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 10 | Denbury Management, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 1999 |
| 11 | Denbury Offshore, Inc. | | Oil & Gas Operator | Nov 2004 |
| 12 | Despot Expl. Inc-Serio Expl Co | | Oil & Gas Operator | Apr 1990 |
| 13 | Despot Exploration, Inc. | | Oil & Gas Operator | Apr 1990 |
| 14 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 15 | Devon Energy Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2009 |
| 16 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 17 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 18 | Dexco, Inc. | | Oil & Gas Operator | May 1990 |
| 19 | Diamex Company | | Oil & Gas Operator | Oct 1982 |
| 20 | Diamond Shamrock Corp | Amarillo, TX 79105 | Oil & Gas Operator | Jan 1987 |
| 21 | Dimension Energy Co., L.L.C. | | Oil & Gas Operator | Dec 2024 |
| 22 | Dixie Well Service, Inc. | | Oil & Gas Operator | Jul 1995 |
| 23 | Dune Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Jun 2016 |
| 24 | Dunhill Resources, Inc. | | Oil & Gas Operator | Nov 2005 |
| 25 | Dynamic Exploration, Inc. | | Oil & Gas Operator | Oct 2003 |
| 26 | Dynamic Offshore Resources, LLC | Houston, TX 77042 | Oil & Gas Operator | Oct 2025 |