| 1 | D & B Oil Company | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 2 | D & J Oil Company | Kermit, TX 79745 | Oil & Gas Operator | Oct 2025 |
| 3 | Dallas Production, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2021 |
| 4 | Daniel Oil & Gas | Granbury, TX 76049 | Oil & Gas Operator | Oct 2010 |
| 5 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 6 | De Compiegne Prop. Co. 20, The | Midland, TX 79702 | Oil Operator | Oct 2019 |
| 7 | Delek Energy Systems Us Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2011 |
| 8 | Delta Oil & Gas Company | Breckenridge, TX 76424 | Oil & Gas Operator | Apr 2003 |
| 9 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 10 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 11 | Devon Gas Services, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Nov 2015 |
| 12 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 13 | Diamondback E&P LLC | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 14 | Dinero Operating Co | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 15 | Discovery Operating Inc | Midland, TX 79705 | Oil & Gas Operator | Oct 2025 |
| 16 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 17 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 18 | Double Eagle Operating, LLC | Fort Worth, TX 76113 | Oil & Gas Operator | Oct 2025 |
| 19 | Double R Oil Co. | Charlotte, TX 78011 | Oil & Gas Operator | May 2010 |
| 20 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 21 | DRH Properties LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 2014 |
| 22 | DSR Oil & Gas, Inc. | Monahans, TX 79756 | Oil & Gas Operator | Oct 2025 |
| 23 | Dudley Oil Co. | Crane, TX 79731 | Oil & Gas Operator | Jan 2006 |
| 24 | Dugan Production Corp | Farmington, NM 87499 | Oil & Gas Operator | Jul 2025 |
| 25 | Dunigan Petroleum, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 26 | Durham, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jul 2016 |