| 201 | Toce Oil Company | | Oil & Gas Operator | Dec 2014 |
| 202 | Transcontinental Gas P/L Corp. | | Oil & Gas Operator | Dec 2009 |
| 203 | Transcontinental Gas Pipeline Co LLC | | Oil Operator | Jan 2025 |
| 204 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 205 | Triumph Energy, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Nov 2015 |
| 206 | U.S. Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 207 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 208 | Union Texas Petroleum Corp. | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 209 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Apr 2025 |
| 210 | Us Oil & Gas Inc | Marietta, OH 45750 | Oil & Gas Operator | Feb 2025 |
| 211 | Wagner & Brown | Midland, TX 79702 | Oil & Gas Operator | Aug 2014 |
| 212 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |
| 213 | Warhorse Oil & Gas, LLC | | Oil & Gas Operator | Dec 2018 |
| 214 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 215 | Whiskey Bay Oil Company | | Oil & Gas Operator | May 1990 |
| 216 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 217 | Whitton Company, Inc. | | Oil & Gas Operator | Jul 2020 |
| 218 | Will-Drill Production Co., Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Apr 2025 |