| 1 | T & T Production Co. | Victoria, TX 77902 | Oil & Gas Operator | Feb 1995 |
| 2 | T.D. Operating Company, Inc. | New Braunfels, TX 78130 | Oil & Gas Operator | Nov 1999 |
| 3 | Tabbs Bay Production Company | Houston, TX 77019 | Oil Operator | Oct 2025 |
| 4 | Tandem Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 5 | Tap Operating Company, Inc. | Mexia, TX 76667 | Oil & Gas Operator | May 1995 |
| 6 | Tartan Resources Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 1995 |
| 7 | Tecolote Petroleum Corp.,Inc. | Friendswood, TX 77546 | Oil & Gas Operator | Mar 2011 |
| 8 | Tejas Gas Pipeline Company | Houston, TX 77010 | Oil & Gas Operator | Apr 1998 |
| 9 | Tejas Gas Pipeline, L.P. | Houston, TX 77002 | Oil & Gas Operator | Feb 2002 |
| 10 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Oct 2025 |
| 11 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 12 | Texakota, Inc. | Houston, TX 77098 | Oil & Gas Operator | Mar 2021 |
| 13 | Texana Operating Company | Houston, TX 77090 | Oil & Gas Operator | Oct 2025 |
| 14 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Oct 2025 |
| 15 | Texas Gas Resources, Inc. | Houston, TX 77292 | Oil & Gas Operator | Jul 2009 |
| 16 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 17 | Texas Oil Resources Oper, LLC | Houston, TX 77024 | Oil Operator | Oct 2025 |
| 18 | Texlan Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Nov 1994 |
| 19 | Texstar North America, Inc. | Waynesboro, MS 39367 | Oil & Gas Operator | Aug 1994 |
| 20 | TGX Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2004 |
| 21 | Thornberry Oilfield Service, Inc | Conroe, TX 77302 | Oil & Gas Operator | Aug 2003 |
| 22 | Thorp Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2014 |
| 23 | Titan Petroleum, Inc. | Tomball, TX 77375 | Oil & Gas Operator | Nov 2004 |
| 24 | Tomlinson, Thomas K. Inc. | Port Lavaca, TX 77979 | Oil & Gas Operator | Jul 2003 |
| 25 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 26 | Torrent Oil LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 27 | Tortuga Operating Company | Houston, TX 77055 | Oil & Gas Operator | Oct 2025 |
| 28 | Trace Operating, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Oct 2025 |
| 29 | Transtexas Gas Corporation | Houston, TX 77265 | Oil & Gas Operator | Aug 2005 |
| 30 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |
| 31 | Travis | Houston, TX 77057 | Oil Operator | Oct 2025 |
| 32 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Oct 2025 |
| 33 | Tri City Oil Co., LLC | Kountze, TX 77625 | Oil Operator | Oct 2025 |
| 34 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 35 | Tri-C Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 36 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 37 | TT Operating, LLC | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 38 | Tucker Operating Co., Inc. | Victoria, TX 77903 | Oil & Gas Operator | Oct 2025 |
| 39 | Txco Resources Inc. | San Antonio, TX 78280 | Oil & Gas Operator | Oct 2025 |