| 1 | T. N. T. Inc. | | Oil & Gas Operator | Jan 1987 |
| 2 | Tabco Exploration Inc. | New Orleans, LA 70131 | Oil & Gas Operator | Dec 1998 |
| 3 | Talon Energy LLC | | Gas Operator | Jan 2020 |
| 4 | Talos Energy Offshore LLC | | Oil & Gas Operator | Jan 2025 |
| 5 | Talos Third Coast LLC | | Oil & Gas Operator | Dec 2024 |
| 6 | Tana Exploration Company LLC | Dallas, TX 75219 | Oil & Gas Operator | Aug 2021 |
| 7 | Tchefuncte Natural Resources, L.L.C. | | Oil & Gas Operator | Aug 2011 |
| 8 | Tecpetrol Operating LLC | Houston, TX 77027 | Oil & Gas Operator | Dec 2015 |
| 9 | Telico Minerals, L.L.C. | | Oil & Gas Operator | Oct 2019 |
| 10 | Tellus Operating Group, LLC | | Oil & Gas Operator | Nov 2025 |
| 11 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Nov 2025 |
| 12 | Tennessee Gas Pipeline Company | | Oil & Gas Operator | Dec 2011 |
| 13 | Tennessee Gas Pipeline Company, LLC | | Oil Operator | Dec 2024 |
| 14 | Terra Resources, Inc. | Casper, WY 82601 | Oil & Gas Operator | Jun 1990 |
| 15 | Tesoro Petroleum Corporation | | Oil & Gas Operator | May 1982 |
| 16 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Feb 2026 |
| 17 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 18 | Texas Crude & Dale Gas Expl | | Oil & Gas Operator | Dec 1984 |
| 19 | Texas Crude Operator, Inc. | Houston, TX 77098 | Oil & Gas Operator | Aug 2017 |
| 20 | Texas Crude, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 1995 |
| 21 | Texas Crude-Rebstock & Reeves | | Oil & Gas Operator | Feb 1980 |
| 22 | Texas Eastern Transm. Corp. | | Oil & Gas Operator | Dec 2002 |
| 23 | Texas Energy & Environmental Inc | Houston, TX 77269 | Oil & Gas Operator | Oct 1998 |
| 24 | Texas Gas Exploration Corp. | | Oil & Gas Operator | Nov 1986 |
| 25 | Texas Gas Transmission Corp. | | Oil Operator | Aug 2003 |
| 26 | Texas Meridian Res. Expl., Inc. | Houston, TX 77079 | Oil & Gas Operator | Jun 1998 |
| 27 | Texas Pacific Oil Co. | | Oil & Gas Operator | Dec 1980 |
| 28 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | Feb 2026 |
| 29 | Texoil Company | | Oil & Gas Operator | Dec 2000 |
| 30 | The Meridian Res. & Exp. LLC | | Oil & Gas Operator | Sep 2010 |
| 31 | The Meridian Resource & Exp Co | | Oil & Gas Operator | Dec 2000 |
| 32 | The Stone Oil Corporation | | Oil & Gas Operator | May 1985 |
| 33 | The Stone Petro Corp-Toce Oil | | Oil & Gas Operator | Oct 1984 |
| 34 | The Superior Oc WM Scully Etal | | Oil & Gas Operator | Apr 1986 |
| 35 | Tillman A. Rousse | | Oil Operator | Jan 1990 |
| 36 | Tillman A. Rousse, Inc. | | Oil Operator | Apr 2001 |
| 37 | Tipco | Shreveport, LA 71104-3047 | Oil & Gas Operator | May 1988 |
| 38 | Toce Oil Company | | Oil & Gas Operator | Dec 2014 |
| 39 | Tola Production Company | Dallas, TX 75367 | Oil & Gas Operator | Feb 2026 |
| 40 | Tolar Corporation | | Oil & Gas Operator | Sep 1999 |
| 41 | Tolar Energy, L.L.C. | | Oil & Gas Operator | Dec 2001 |
| 42 | Tom Brown Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 2004 |
| 43 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 44 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 45 | Tradition Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2017 |
| 46 | Trafalgar House Oil & Gas Inc | Houston, TX 77002-7346 | Oil & Gas Operator | Jan 1992 |
| 47 | Trans Ocean Oil, Inc. | | Oil & Gas Operator | Sep 1980 |
| 48 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 49 | Trigon Exploration, Inc. | | Oil & Gas Operator | Jan 1999 |
| 50 | Triton Oil & Gas Corp. | Houston, TX 77002 | Oil & Gas Operator | Nov 2014 |
| 51 | Triumph Energy Inc | Lafayette, LA 70505 | Oil & Gas Operator | Nov 2015 |
| 52 | TXP Operating Co. | | Oil & Gas Operator | Jul 1992 |