| 1 | Tartan Resources Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 1995 |
| 2 | Tenex Corporation | Houston, TX 77227 | Oil & Gas Operator | Dec 2007 |
| 3 | Tex-Ok Energy, Limited Partnership | Cody, WY 82414 | Oil & Gas Operator | Jul 2025 |
| 4 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 5 | Texakoma E & P, LLC | Plano, TX 75024 | Oil & Gas Operator | Oct 2025 |
| 6 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 7 | Texakoma Operating, L.P. | Plano, TX 75024 | Oil & Gas Operator | Mar 2025 |
| 8 | Texana Operating Company | Houston, TX 77090 | Oil & Gas Operator | Oct 2025 |
| 9 | Texas Onshore Energy, Inc. | Austin, TX 78704 | Oil & Gas Operator | Oct 2025 |
| 10 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 11 | Texas Secondary Oil Corporation | Devine, TX 78016 | Oil & Gas Operator | Oct 2025 |
| 12 | Texron Operating, LLC | Bulverde, TX 78163 | Oil & Gas Operator | Oct 2025 |
| 13 | Texstar North America, Inc. | Waynesboro, MS 39367 | Oil & Gas Operator | Aug 1994 |
| 14 | Thorp Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2014 |
| 15 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | Oct 2025 |
| 16 | Titan Petroleum, Inc. | Tomball, TX 77375 | Oil & Gas Operator | Nov 2004 |
| 17 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 18 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 19 | Tritex Production Co. | Iowa Park, TX 76367 | Oil & Gas Operator | Jan 2013 |
| 20 | Tucker Operating Co., Inc. | Victoria, TX 77903 | Oil & Gas Operator | Oct 2025 |
| 21 | Tuskar (Texas), Inc. | Nichols Hill, OK 73116 | Oil & Gas Operator | Jan 2016 |