| 1 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Sep 2026 |
| 2 | Taylor-McIlhenny Oper. Co., Inc. | Lewisville, TX 75029 | Oil & Gas Operator | Jan 1996 |
| 3 | TC3 Energy Services Company | Bryan, TX 77805 | Oil & Gas Operator | Jan 2005 |
| 4 | Tejas Operating Company, Inc. | Houston, TX 77257 | Oil & Gas Operator | May 1995 |
| 5 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 6 | Texas Presco, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Nov 2025 |
| 7 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 8 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2026 |
| 9 | Treadstone Energy Partners, LLC | Houston, TX 77070 | Oil & Gas Operator | Jun 2016 |
| 10 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Sep 2026 |
| 11 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | Sep 2026 |
| 12 | Txco Resources Inc. | San Antonio, TX 78280 | Oil & Gas Operator | Sep 2026 |
| 13 | Txu Lone Star Pipeline | Dallas, TX 75201 | Oil & Gas Operator | Oct 2003 |