| 1 | Taurus Petroleum | | Oil & Gas Operator | Jul 1987 |
| 2 | Taylor Energy Co. | | Oil & Gas Operator | May 1991 |
| 3 | Tee Operating Company | | Oil & Gas Operator | Jun 1989 |
| 4 | Tejas Production Company | | Oil Operator | Nov 1979 |
| 5 | Tenison Oil Company | Abilene, TX 79605 | Oil & Gas Operator | Jun 2025 |
| 6 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Jul 2025 |
| 7 | Terrier Oil Company | | Oil & Gas Operator | Feb 2015 |
| 8 | Tesoro Petroleum Corporation | | Oil & Gas Operator | May 1982 |
| 9 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 10 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 11 | Texaco Oils, Inc. | Tulsa, OK 74102-2420 | Oil & Gas Operator | Jan 2003 |
| 12 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 13 | Texas Eastern Transm. Corp. | | Oil & Gas Operator | Dec 2002 |
| 14 | Texas General Petroleum Corp | | Oil & Gas Operator | Aug 1984 |
| 15 | Texas Meridian Operating Co. Inc | Houston, TX 77079 | Oil & Gas Operator | Oct 1993 |
| 16 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 17 | Texegy Operating Company LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2024 |
| 18 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 19 | The Southern Louisiana Expl. Company LLC | | Oil & Gas Operator | Nov 2024 |
| 20 | Three Sisters Investments, LTD | | Oil & Gas Operator | Oct 1989 |
| 21 | Todd Oil Corp. Of La. Inc. | | Oil & Gas Operator | Jul 2000 |
| 22 | Tom West | | Oil & Gas Operator | Nov 1989 |
| 23 | Trace Operators, Inc. | | Oil & Gas Operator | Nov 2024 |
| 24 | Traillour Oil Co. | | Oil & Gas Operator | Mar 1990 |
| 25 | Trans-Sabine Pipeline Corp | | Oil Operator | Mar 2009 |
| 26 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Oct 2025 |
| 27 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 28 | Tri-C Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 29 | Triumph Energy, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Nov 2015 |
| 30 | Trunkline Gas Company | | Oil Operator | Mar 2008 |
| 31 | Tryvest, Inc. | | Oil & Gas Operator | Sep 1991 |
| 32 | Tundra Energy | | Oil Operator | Jan 2025 |
| 33 | Turnkey E&P Corporation | | Oil & Gas Operator | Dec 2010 |
| 34 | Txla Energy, Inc. | Houston, TX 77018 | Oil & Gas Operator | Oct 2025 |
| 35 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |