| 1 | D & L Operating Co. | Bangs, TX 76823 | Oil & Gas Operator | Nov 2022 |
| 2 | D.J. & T. Energy | Abilene, TX 79601 | Oil & Gas Operator | Oct 2025 |
| 3 | D.N.I. | Bangs, TX 76823 | Oil & Gas Operator | Oct 2025 |
| 4 | Daleco Resources, Inc. | Lewisville, TX 75067 | Oil & Gas Operator | Mar 2008 |
| 5 | Davco Oil LLC | Fort Worth, TX 76108 | Oil & Gas Operator | Oct 2025 |
| 6 | DBC Operating Company LLC | Midlothian, TX 76065 | Oil & Gas Operator | Oct 2025 |
| 7 | Del Mar Energy, Inc. | Van Alstyne, TX 75495 | Oil & Gas Operator | Oct 2025 |
| 8 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 9 | Denhart & Denhart | Brownwood, TX 76804 | Oil & Gas Operator | Dec 2001 |
| 10 | Denteco Oil Company LLC | Abilene, TX 79604 | Oil & Gas Operator | Oct 2025 |
| 11 | Diamond Mineral Investments Inc. | Bangs, TX 76823 | Gas Operator | Feb 2008 |
| 12 | DJM Beasley Well Service | Tuscola, TX 79562 | Oil Operator | Oct 2025 |
| 13 | DMV Pipeline LLC | Lipan, TX 76462 | Oil & Gas Operator | Oct 2025 |
| 14 | Doc Oil | Brownwood, TX 76801 | Oil & Gas Operator | Oct 2019 |
| 15 | Domino Operations, Inc. | Abilene, TX 79603 | Oil & Gas Operator | Oct 2025 |
| 16 | Dominy Oil Co., Inc. | Fort Worth, TX 76185 | Oil & Gas Operator | Oct 1999 |
| 17 | Dorondoco Operating Co., Inc. | Brownwood, TX 76801 | Oil & Gas Operator | May 1994 |
| 18 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | Oct 2025 |
| 19 | Double M Petroproperties, Inc. | Haskell, TX 79521 | Oil & Gas Operator | Oct 2025 |
| 20 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 21 | Down-Hole Pump Service Co., Inc. | Fort Worth, TX 76109 | Oil & Gas Operator | Oct 2025 |
| 22 | Duncan Drilling Co. | Big Spring, TX 79721 | Oil & Gas Operator | Oct 2025 |
| 23 | Durango Operating Co., Inc. | Abilene, TX 79604 | Oil & Gas Operator | Feb 2002 |
| 24 | Durham, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jul 2016 |
| 25 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |