| 1 | D & W Trucking Company | De Berry, TX 75639 | Oil Operator | Mar 2003 |
| 2 | D-S-B Properties, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Sep 2014 |
| 3 | D90 Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 4 | Daco Oil | Joinerville, TX 75658 | Oil & Gas Operator | Aug 2019 |
| 5 | Dallas Production, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2021 |
| 6 | Danmark Energy Services, Inc. | White Oak, TX 75693 | Oil & Gas Operator | Apr 2021 |
| 7 | Davis Operating Company | Elysian Field, TX 75642 | Oil & Gas Operator | Oct 2025 |
| 8 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 9 | Dearing, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2021 |
| 10 | Deep Rock Resources, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Oct 2025 |
| 11 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 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 | Diamond Energy, Inc. | Sherman, TX 75091 | Oil & Gas Operator | Oct 2025 |
| 15 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Oct 2025 |
| 16 | Dixie Lake Operating, LLC | Longview, TX 75606 | Gas Operator | Oct 2025 |
| 17 | DJD Drilling Corporation | Graham, TX 76450 | Oil Operator | Jan 2010 |
| 18 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 19 | DNR Oil And Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Aug 2025 |
| 20 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 21 | Donnell Pipe & Supply Co/TX Corp | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2008 |
| 22 | Dorado Operating Inc. | Dallas, TX 75225 | Oil & Gas Operator | Apr 2011 |
| 23 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | Oct 2025 |
| 24 | Double L Contractors, LLC | Carthage, TX 75633 | Oil Operator | Oct 2025 |
| 25 | Dove Creek Energy, Inc. | Fort Worth, TX 76121 | Oil & Gas Operator | Oct 2025 |
| 26 | Dowden, T. L. | Henderson, TX 75652 | Oil & Gas Operator | Oct 2025 |
| 27 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |