| 201 | Talon Development Company | Boerne, TX 78006 | Oil & Gas Operator | Sep 2007 |
| 202 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 203 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 204 | Texas Independent Explor LTD. | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 205 | Texas Independent Explor., Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2002 |
| 206 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 207 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 208 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 209 | Total Minatome Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 1998 |
| 210 | Tradition Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2017 |
| 211 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 212 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 213 | Trio Operating Company, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2006 |
| 214 | Trivista Operating LLC | Giddings, TX 78942 | Oil & Gas Operator | May 2025 |
| 215 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 216 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 217 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 218 | Vess Oil Corporation | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 219 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Feb 2025 |
| 220 | Virtex Operating Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2023 |
| 221 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 222 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 223 | Warren Production Services | Caldwell, TX 77836 | Oil & Gas Operator | May 2025 |
| 224 | Weber Energy Corporation | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 225 | Westco Oil Company | Ozona, TX 76943 | Oil & Gas Operator | May 2025 |
| 226 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 227 | Westpark Petroleum, Inc. | Austin, TX 78755 | Oil & Gas Operator | May 2025 |
| 228 | Weststar Oil & Gas Inc | Edmond, OK 73013 | Oil & Gas Operator | Mar 2025 |
| 229 | WG Operating, Inc. | Tulsa, OK 74153 | Oil & Gas Operator | May 2012 |
| 230 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | May 2025 |
| 231 | Wildfire Energy Operating LLC | Houston, TX 77224 | Oil & Gas Operator | May 2025 |
| 232 | Wind River Resources Inc | Tulsa, OK 74136-6381 | Oil & Gas Operator | Jun 2010 |
| 233 | Winn Exploration Co., Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 234 | Woodlands Oil And Gas Inc. | The Woodlands, TX 77380 | Gas Operator | Jan 2014 |
| 235 | Wortham Oil & Gas | Conroe, TX 77301 | Oil & Gas Operator | May 2025 |
| 236 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 237 | Zarvona Energy LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 238 | Zaza Energy, LLC | Houston, TX 77010 | Oil & Gas Operator | May 2025 |
| 239 | Zingara Grimes, LLC | Dallas, TX 75205 | Oil & Gas Operator | May 2025 |