| 301 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 302 | San Patricio Corporation | Dinero, TX 78350 | Oil & Gas Operator | Sep 2003 |
| 303 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 304 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 305 | Sandia Energy Corporation-NM | Holdenville, OK 74848 | Oil & Gas Operator | Aug 2003 |
| 306 | Sandman Exploration, L.L.C. | Georgetown, TX 78627 | Oil & Gas Operator | Jul 2025 |
| 307 | Sandpoint Operating, LLC | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 308 | Sbog, LLC | Granbury, TX 76048 | Oil & Gas Operator | Feb 2021 |
| 309 | Sea Eagle Ford, LLC | Denver, CO 80265 | Oil & Gas Operator | Jun 2022 |
| 310 | Sedco Resources Inc | Kerrville, TX 78029 | Oil & Gas Operator | Jul 2025 |
| 311 | Senora Resources, Inc. | Dime Box, TX 77853 | Oil & Gas Operator | Jul 2025 |
| 312 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 313 | Shield Petroleum | College Sta, TX 77845 | Oil & Gas Operator | Jul 2025 |
| 314 | Shoreham Oil & Gas Company, Inc. | Katy, TX 77492 | Oil & Gas Operator | Jul 2025 |
| 315 | Showdown Energy Corporation | Dallas, TX 75230 | Oil & Gas Operator | Aug 2003 |
| 316 | Showdown Operating, Inc. | Dallas, TX 75230 | Oil & Gas Operator | May 1996 |
| 317 | Sierra Resources, LLC | Houston, TX 77219 | Oil & Gas Operator | Aug 2021 |
| 318 | Silver Hill Energy Operating, LLC | Dallas, TX 75201 | Oil & Gas Operator | Jul 2025 |
| 319 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Apr 2025 |
| 320 | Silverbow Resources Oper, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 321 | Single Barrel Oil And Gas LLC | Granbury, TX 76048 | Oil & Gas Operator | Jul 2025 |
| 322 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 323 | SN Ef Maverick, LLC | Houston, TX 77002 | Oil & Gas Operator | Aug 2023 |
| 324 | SN Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 325 | Sojourner Drilling Corporation | Abilene, TX 79604 | Oil & Gas Operator | Jul 2025 |
| 326 | Solano Gas Processing, Inc. | Austin, TX 78759 | Oil & Gas Operator | Aug 1998 |
| 327 | South Oil, Inc. | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 328 | South Texas Limited Partnership | Houston, TX 77060 | Oil & Gas Operator | Feb 1994 |
| 329 | Southern Resource Company | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Mar 2022 |
| 330 | Southwest Oil & Land, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Dec 1999 |
| 331 | Spiller Operating Co., Inc. | Round Rock, TX 78665 | Oil & Gas Operator | May 2015 |
| 332 | Stampede Energy Corp. | Canada, 00100 | Oil & Gas Operator | Mar 2000 |
| 333 | Starr Operating Company | Austin, TX 78759 | Oil & Gas Operator | Jul 2025 |
| 334 | Statoil Texas Onshore Prop LLC | Austin, TX 78730 | Oil & Gas Operator | Dec 2018 |
| 335 | Stinger Oil & Gas Inc. | Sherman Oaks, CA 91403 | Oil & Gas Operator | Oct 2013 |
| 336 | Stonegate Operators, Inc. | Addison, TX 75001 | Oil Operator | Jul 2025 |
| 337 | Stonegate Production Company,LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 338 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Jul 2025 |
| 339 | Sundance Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2014 |
| 340 | Sutton Producing Corp. | San Antonio, TX 78270 | Oil & Gas Operator | Jul 2025 |
| 341 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 342 | Swift Energy Operating, LLC | Houston, TX 77079 | Oil & Gas Operator | Jun 2017 |
| 343 | Sydri Operating, LLC | Dallas, TX 75231 | Oil & Gas Operator | Jul 2025 |
| 344 | Talisman Energy USA Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | May 2016 |
| 345 | Targa Midstream Services LLC | Houston, TX 77002 | Oil Operator | Mar 2023 |
| 346 | Targa Pipeline Mid-Continent LLC | Sulphur, LA 70665 | Oil & Gas Operator | Jun 2018 |
| 347 | Teal Operating, LLC | Dallas, TX 75225 | Oil & Gas Operator | Oct 2021 |
| 348 | Tekna Synergy Corporation | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 349 | Tenexco Inc | Oakbrook Terrace, IL 60181 | Gas Operator | Dec 1998 |
| 350 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 351 | Terrafina Energy, LLC | San Antonio, TX 78280 | Oil & Gas Operator | Jul 2025 |
| 352 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Jul 2025 |
| 353 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 354 | Texan Production Company, Inc. | Canyon Lake, TX 78133 | Oil & Gas Operator | Jul 2025 |
| 355 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | Jul 2025 |
| 356 | Texas Crude Energy, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 2012 |
| 357 | Texas International Oper., LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2013 |
| 358 | Texas Lone Star Petroleum Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Dec 2013 |
| 359 | Texas Refining, Inc. | Houston, TX 77057 | Oil & Gas Operator | Aug 2003 |
| 360 | Texas Secondary Oil Corporation | Devine, TX 78016 | Oil & Gas Operator | Jul 2025 |
| 361 | Texas Southern Petroleum Corp. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 362 | Texokan Operating, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jul 2025 |
| 363 | Thalmann, David Vac Service Inc | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Jul 2025 |
| 364 | Tidal Petroleum, Inc. | Schertz, TX 78154 | Oil & Gas Operator | Jul 2025 |
| 365 | Tide West Oil Company | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2021 |
| 366 | Tipperary Oil & Gas Corp | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 367 | Tiza Energy, Inc. | Austin, TX 78715 | Oil & Gas Operator | Jul 2025 |
| 368 | TNT Petroleum Company, Inc. | Corpus Chrsti, TX 78473 | Oil & Gas Operator | Feb 1996 |
| 369 | Tracker Oil & Gas, Inc. | Bastrop, TX 78602 | Oil & Gas Operator | Jul 2025 |
| 370 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | Jul 2025 |
| 371 | Tri-C Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 372 | Triforce Energy LLC | Littleton, CO 80122 | Oil & Gas Operator | Jul 2025 |
| 373 | Trinity Operating (Usg), LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 374 | Tucker Petroleum, Inc. | Corpus Chrsti, TX 78468 | Oil & Gas Operator | Jul 2025 |
| 375 | Turner, M. O. | San Antonio, TX 78278 | Oil & Gas Operator | Apr 2003 |
| 376 | Tuskar (Texas), Inc. | Nichols Hill, OK 73116 | Oil & Gas Operator | Jan 2016 |
| 377 | TX Petroleum Company | Corpus Chrsti, TX 78412 | Oil & Gas Operator | Apr 1996 |
| 378 | U. S. Operating, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Jul 2025 |
| 379 | U.S.A. Plugging Company | Pearsall, TX 78061 | Oil & Gas Operator | Jul 2025 |
| 380 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 381 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 382 | V/J Oil Company | Yancey, TX 78886 | Oil & Gas Operator | Oct 2015 |
| 383 | Vanguard Permian LLC | Houston, TX 77057 | Oil & Gas Operator | Nov 2018 |
| 384 | Venado Operating Company LLC | Austin, TX 78738 | Oil & Gas Operator | Mar 2022 |
| 385 | Verdun Oil & Gas LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 386 | Verdun Oil Ef II LLC | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 387 | Vermillion Production, Inc. | Pearsall, TX 78061 | Oil & Gas Operator | Jul 2025 |
| 388 | Victoria Operating, Inc. | Victoria, TX 77903 | Oil & Gas Operator | Jul 2025 |
| 389 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 390 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | Jul 2025 |
| 391 | Virtex Operating Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Oct 2023 |
| 392 | Virtex Petroleum Company, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Jan 2008 |
| 393 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 394 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 395 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 396 | WCS Oil & Gas Corporation | Dallas, TX 75209 | Oil & Gas Operator | Aug 2021 |
| 397 | Weber Energy Corporation | Dallas, TX 75219 | Oil & Gas Operator | Feb 2017 |
| 398 | Welder Exploration & Prod., Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Dec 2022 |
| 399 | Welhausen Operating Company, LP | Beeville, TX 78104 | Oil & Gas Operator | Nov 2016 |
| 400 | Wen-Be | Jourdanton, TX 78026 | Oil & Gas Operator | Jul 2025 |