| 1 | Tabco Producing Co. | | Oil & Gas Operator | Jan 1998 |
| 2 | Tammany Oil & Gas LLC | | Oil & Gas Operator | Feb 2005 |
| 3 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 4 | Tecpetrol Operating LLC | Houston, TX 77027 | Oil & Gas Operator | Dec 2015 |
| 5 | Tepco Resources, Inc. | Houston, TX 77027 | Oil & Gas Operator | Sep 2004 |
| 6 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 7 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 8 | Texas Crude, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 1995 |
| 9 | Texas Gas Transmission Corp. | | Oil Operator | Aug 2003 |
| 10 | Texas Gas Transmission LLC | Owensboro, KY 42301 | Oil & Gas Operator | Dec 2024 |
| 11 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 12 | The Dow Chemical Company | | Oil & Gas Operator | Dec 1997 |
| 13 | The Southern Louisiana Expl. Company LLC | | Oil & Gas Operator | Nov 2024 |
| 14 | The Stone Oil Corporation | | Oil & Gas Operator | May 1985 |
| 15 | The Superior Oil Co & Pel-Tex | | Oil & Gas Operator | Apr 1986 |
| 16 | The Termo Company | Long Beach, CA 90801 | Oil & Gas Operator | Aug 2025 |
| 17 | Tiger Petroleum | | Oil Operator | Sep 2002 |
| 18 | Tipco | Shreveport, LA 71104-3047 | Oil & Gas Operator | May 1988 |
| 19 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 20 | Transcontinental Oil Corp. | | Oil & Gas Operator | Sep 1985 |
| 21 | Traver Oil Company | | Oil & Gas Operator | Sep 2000 |
| 22 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 23 | Trigon Exploration, Inc. | | Oil & Gas Operator | Jan 1999 |
| 24 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 25 | TXP Operating Company | | Oil & Gas Operator | Jul 1992 |