| 1 | Tag Operating Company, Inc. | Houston, TX 77092 | Oil & Gas Operator | Dec 2025 |
| 2 | TD Natural Resources LLC | Cuero, TX 77954 | Oil & Gas Operator | Dec 2025 |
| 3 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Dec 2025 |
| 4 | Tejas Gas Pipeline, L.P. | Houston, TX 77002 | Oil & Gas Operator | Feb 2002 |
| 5 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 6 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 7 | Tesoro Expl. & Prod. Company | San Antonio, TX 78216 | Gas Operator | Sep 2010 |
| 8 | Texana Operating Company | Houston, TX 77090 | Oil & Gas Operator | Dec 2025 |
| 9 | Texas Operating Partners LLC | Tomball, TX 77377 | Oil & Gas Operator | Dec 2025 |
| 10 | Texas Southern Petroleum Corp. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Dec 2025 |
| 11 | Texas, Les & Co. | Brenham, TX 77833 | Oil & Gas Operator | Dec 2025 |
| 12 | Texas, Les C., LTD. | Houston, TX 77095 | Oil & Gas Operator | Dec 2006 |
| 13 | Thorp Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2014 |
| 14 | Three C Exploration, LLC | Hebbronville, TX 78361 | Oil & Gas Operator | Dec 2025 |
| 15 | Three-C Oil And Gas | Hebbronville, TX 78361 | Oil & Gas Operator | Dec 2025 |
| 16 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 17 | Transamerican Natural Gas Corp. | Houston, TX 77032 | Oil & Gas Operator | Aug 2000 |
| 18 | Transpacific Energy, LLC | Katy, TX 77450 | Oil & Gas Operator | Dec 2025 |
| 19 | Transtexas Gas Corporation | Houston, TX 77265 | Oil & Gas Operator | Aug 2005 |
| 20 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |
| 21 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 22 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |