| 301 | Sullivan, Hollis R. Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2009 |
| 302 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | May 2025 |
| 303 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | May 2025 |
| 304 | Sweet Crude Operating LLC | Brenham, TX 77834 | Oil & Gas Operator | May 2025 |
| 305 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 306 | T & C Oil, Inc. | Lubbock, TX 79424 | Oil & Gas Operator | Apr 2024 |
| 307 | TC Energy LLC | Covington, OK 73730-2116 | Oil & Gas Operator | Sep 2014 |
| 308 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 309 | Telesis Operating Co. | Fort Worth, TX 76116 | Oil & Gas Operator | May 2025 |
| 310 | Terrell Oil & Gas Production Co. | Hamlin, TX 79520 | Oil & Gas Operator | May 2025 |
| 311 | Tex-R Energy, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Feb 2021 |
| 312 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 313 | Texas Operating & Consult., LLC | Abilene, TX 79608 | Oil & Gas Operator | Feb 2018 |
| 314 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 315 | Texzona Oil & Gas, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Dec 1997 |
| 316 | Thompson, Richard W. Inc. | Plano, TX 75024 | Oil & Gas Operator | May 2025 |
| 317 | Three R Oil Company | Post, TX 79356 | Oil & Gas Operator | May 2025 |
| 318 | Three Span Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 319 | Three-B Oil Company, The | Monahans, TX 79756 | Oil & Gas Operator | May 2025 |
| 320 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 321 | TLH Production LLC | Abilene, TX 79602 | Oil & Gas Operator | May 2025 |
| 322 | TMBR/Sharp Drilling, Inc. | Midland, TX 79703 | Oil & Gas Operator | Feb 2004 |
| 323 | Tong Petrotech Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2025 |
| 324 | Tracer Energy, Inc. | Graham, TX 76450 | Oil & Gas Operator | Nov 1998 |
| 325 | Tracer Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 326 | Trio Consulting & Management,LLC | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 327 | Trio Operating Company, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 2006 |
| 328 | Tucker Resources, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Aug 2003 |
| 329 | Tuthill & Barbee | Amarillo, TX 79101 | Oil & Gas Operator | Nov 1994 |
| 330 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 331 | Unitex Oil & Gas, L.L.C. | Midland, TX 79701 | Oil & Gas Operator | May 2025 |
| 332 | V-F Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 333 | VX Operating, LLC | Abilene, TX 79605 | Oil & Gas Operator | May 2025 |
| 334 | W.O.G., Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 335 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 336 | Walsh & Watts Inc | Aledo, TX 76008 | Oil & Gas Operator | May 2025 |
| 337 | Walter Exploration Inc | Dallas, TX 75206 | Oil & Gas Operator | May 2009 |
| 338 | West Texas Oil And Gas Corp. | Houston, TX 77056 | Oil & Gas Operator | Feb 2014 |
| 339 | West Texas Oil And Gas Oper.,Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2024 |
| 340 | Western Reserves Oil Co Inc | Midland, TX 79705 | Oil & Gas Operator | Oct 2020 |
| 341 | Westland Oil Development Corp. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 342 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Jan 2025 |
| 343 | Willow Creek Resources, Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2009 |
| 344 | Winn Operating, LLC | Kilgore, TX 75663 | Oil & Gas Operator | May 2025 |
| 345 | WJC, Inc. | Post, TX 79356 | Oil & Gas Operator | May 2025 |
| 346 | WMS Oil Company | Post, TX 79356 | Oil & Gas Operator | May 2019 |
| 347 | Woods Operating Co., Inc. | Shreveport, LA 71136 | Oil & Gas Operator | Dec 2020 |
| 348 | WTP Energy, Inc. | Snyder, TX 79549 | Oil & Gas Operator | May 2025 |
| 349 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 350 | Yates Industries, LLC | Santa Fe, NM 87501 | Oil & Gas Operator | May 2025 |
| 351 | Young Marshall R Oil Co | Fort Worth, TX 76107 | Oil & Gas Operator | Mar 2011 |
| 352 | Zachry Oil And Gas Properties | Midland, TX 79708 | Oil & Gas Operator | May 2025 |