| 301 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 302 | Rock Bottom Oil, GP, L.L.C. | Nacogdoches, TX 75963 | Oil & Gas Operator | Mar 2026 |
| 303 | Roosth & Genecov Production Co. | Tyler, TX 75710 | Oil & Gas Operator | Aug 2003 |
| 304 | Roosth Production Co. | Tyler, TX 75711 | Oil & Gas Operator | Mar 2026 |
| 305 | Rose City Resources, LLC | Tyler, TX 75703 | Oil & Gas Operator | Mar 2026 |
| 306 | Roseland Oil & Gas Inc | Rockwall, TX 75087 | Oil & Gas Operator | Feb 2003 |
| 307 | Rosewood Resources Inc | Dallas, TX 75201 | Oil & Gas Operator | Mar 2026 |
| 308 | Ross-Rippy | Tyler, TX 75702 | Oil & Gas Operator | Oct 2002 |
| 309 | Rowan, Al | Van, TX 75790 | Oil & Gas Operator | Apr 2021 |
| 310 | Rowan-Ungerecht, Inc. | Van, TX 75790 | Oil & Gas Operator | Sep 1993 |
| 311 | Rush Creek Operating LLC | McKinney, TX 75070 | Oil & Gas Operator | Mar 2026 |
| 312 | Sabio Oil & Gas Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jan 1998 |
| 313 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 314 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 315 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 316 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2026 |
| 317 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2025 |
| 318 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Mar 2026 |
| 319 | SDG Operating Company, Inc | Tyler, TX 75701 | Oil & Gas Operator | Mar 2026 |
| 320 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 321 | Seistech Development, Inc. | Midland, TX 79701 | Oil & Gas Operator | May 2007 |
| 322 | Shelby Production Co. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2009 |
| 323 | Shelby, Michael H. | Shreveport, LA 71101 | Oil & Gas Operator | Mar 2026 |
| 324 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Mar 2026 |
| 325 | Shifflett Operating Company | Snyder, TX 79550 | Oil & Gas Operator | Mar 2026 |
| 326 | Shoco Production LLC | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2026 |
| 327 | Shoco Production, L.P. | Kilgore, TX 75663 | Oil & Gas Operator | May 2020 |
| 328 | SHWJ Oil & Gas Co., Inc. | Oil City, LA 71061 | Oil Operator | Mar 2026 |
| 329 | Sikes Operating, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Jun 2003 |
| 330 | Siroco Operating Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2010 |
| 331 | Skidmore Exploration, Inc. | Dallas, TX 75219 | Oil & Gas Operator | Jul 1997 |
| 332 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 333 | SND Operating, L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2026 |
| 334 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 335 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 336 | Southwest Operating, Inc.-Tyler | Tyler, TX 75701 | Oil & Gas Operator | Mar 2026 |
| 337 | Southwestern Energy Prod Co | Houston, TX 77032 | Oil & Gas Operator | Jun 2015 |
| 338 | Spartan Operating Company, Inc. | Tyler, TX 75702 | Oil & Gas Operator | Feb 2013 |
| 339 | Spence, Ralph Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Jun 2023 |
| 340 | St. Mary Land & Exploration Co | Denver, CO 80201 | Oil & Gas Operator | Jun 2010 |
| 341 | Staub, Larry | Richardson, TX 75080 | Oil & Gas Operator | Aug 2003 |
| 342 | Staub, Larry, Inc. | Azle, TX 76020 | Oil & Gas Operator | Mar 2026 |
| 343 | Strago Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Aug 1994 |
| 344 | Stratco Operating Co Inc | Austin, TX 78701 | Oil & Gas Operator | Mar 2026 |
| 345 | Stroud Petroleum, Inc. | Shreveport, LA 71162 | Oil & Gas Operator | Mar 2026 |
| 346 | Suemaur Expl. & Prod., LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2024 |
| 347 | Sunland Production Company, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2026 |
| 348 | Supreme Energy Company, Inc. | Abilene, TX 79601 | Oil & Gas Operator | Mar 2026 |
| 349 | SW Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Sep 2000 |
| 350 | Swanson Operating, Inc. | Holliday, TX 76366 | Oil Operator | Mar 2026 |
| 351 | Swanson, Tom | Electra, TX 76360 | Oil & Gas Operator | Oct 2004 |
| 352 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Mar 2026 |
| 353 | Tate, Larry V. Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Apr 2002 |
| 354 | TDX Energy, LLC | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2024 |
| 355 | Teco Operating Company | Athens, TX 75751 | Oil & Gas Operator | Jun 2001 |
| 356 | Tengasco, Inc. | Houston, TX 77063 | Oil & Gas Operator | Sep 2025 |
| 357 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 358 | Texaco E & P Inc. | Houston, TX 77099 | Oil & Gas Operator | Mar 2026 |
| 359 | Texas Utilities Fuel Co. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2018 |
| 360 | Texas, Les & Co. | Brenham, TX 77833 | Oil & Gas Operator | Mar 2026 |
| 361 | TGNR East Texas LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2026 |
| 362 | Tiza Energy, Inc. | Austin, TX 78715 | Oil & Gas Operator | Mar 2026 |
| 363 | TMR Exploration, Inc. | Bossier City, LA 71171 | Oil & Gas Operator | Sep 2025 |
| 364 | Total E&P USA, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 2025 |
| 365 | Tower Resources Inc | Conroe, TX 77304 | Oil & Gas Operator | Mar 2026 |
| 366 | Tracy Production | Lindale, TX 75771 | Oil & Gas Operator | Mar 2026 |
| 367 | Transatlantic Petr (USA) Corp. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2026 |
| 368 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 369 | Tri-C Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Mar 2026 |
| 370 | Trinity Gas Storage, LLC | Flower Mound, TX 75028 | Oil & Gas Operator | Mar 2026 |
| 371 | Triple "B" Production DRLG Inc | Poynor, TX 75782 | Oil & Gas Operator | Sep 2022 |
| 372 | Triton Oil & Gas Corp. | Houston, TX 77002 | Oil & Gas Operator | Nov 2014 |
| 373 | Trueblood Resources, Inc. | Denver, CO 80222 | Oil & Gas Operator | Mar 2026 |
| 374 | Tsar Energy, LLC | Dallas, TX 75205 | Oil & Gas Operator | Mar 2026 |
| 375 | TTK Energy LLC | Kilgore, TX 75663 | Oil Operator | Mar 2026 |
| 376 | Tuthill & Barbee | Amarillo, TX 79101 | Oil & Gas Operator | Nov 1994 |
| 377 | Twin Eagle Petroleum Corp | Tulsa, OK 74136 | Oil & Gas Operator | Jun 2002 |
| 378 | Txu Fuel Company | Dallas, TX 75201 | Oil & Gas Operator | May 2004 |
| 379 | Txu Gas Company | Dallas, TX 75201 | Oil & Gas Operator | Sep 2004 |
| 380 | Txu Lone Star Pipeline | Dallas, TX 75201 | Oil & Gas Operator | Oct 2003 |
| 381 | U.S. Enercorp, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2019 |
| 382 | Union Gas Operating Company | Spring, TX 77391 | Oil & Gas Operator | Mar 2026 |
| 383 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jan 2001 |
| 384 | Universal Resources Corp. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jan 2000 |
| 385 | Uosi Operating, Inc. | Lovelady, TX 75851 | Oil & Gas Operator | Mar 2026 |
| 386 | Uphill Consulting LLC | Pearland, TX 77584 | Oil & Gas Operator | Mar 2026 |
| 387 | Upstream Resource Partners, LLC | Elkhart, TX 75839 | Oil Operator | Mar 2026 |
| 388 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Mar 2026 |
| 389 | Valence Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2026 |
| 390 | Vanguard Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Aug 2019 |
| 391 | Vaughn Petroleum, Inc. | Dallas, TX 75219 | Oil & Gas Operator | May 2004 |
| 392 | Vec Operating, LLC | Henderson, TX 75654 | Oil & Gas Operator | Mar 2026 |
| 393 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | Mar 2026 |
| 394 | Victory Oil & Gas Inc | Gun Barrel Cy, TX 75156 | Oil & Gas Operator | Mar 2026 |
| 395 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 396 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | Mar 2026 |
| 397 | W & W Services, Inc. | Palestine, TX 75802 | Oil & Gas Operator | Mar 2008 |
| 398 | W.D. Oil Company | Pampa, TX 79066 | Oil & Gas Operator | Oct 2001 |
| 399 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 400 | Wallis Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Mar 2026 |