| 301 | Rex Energy Operating Corp. | State College, PA 16801 | Oil & Gas Operator | Jun 2012 |
| 302 | Rheaco Oil Company, LTD. | Sourlake, TX 77659 | Oil Operator | May 2025 |
| 303 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 304 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 305 | Roosth Production Co. | Tyler, TX 75711 | Oil & Gas Operator | May 2025 |
| 306 | Rotation, Incorporated | Houston, TX 77057 | Oil & Gas Operator | Mar 2023 |
| 307 | Rover Petroleum Operating, LLC | Plano, TX 75075 | Oil & Gas Operator | May 2025 |
| 308 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 309 | Royal Petroleum | Baytown, TX 77521 | Oil & Gas Operator | Aug 2003 |
| 310 | Royal Production Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | May 2025 |
| 311 | S & S Operating Company, Inc. | Winnie, TX 77665 | Oil & Gas Operator | May 2025 |
| 312 | S & V Operating | Zephyr, TX 76890 | Oil & Gas Operator | May 2025 |
| 313 | S & Y Production Co. | Liberty, TX 77575 | Oil & Gas Operator | Jul 1996 |
| 314 | S. P. Y. Oil Co. | Batson, TX 77519 | Oil & Gas Operator | Mar 2002 |
| 315 | Sabinal Resources, Inc. | Kingwood, TX 77339 | Oil & Gas Operator | May 2025 |
| 316 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | May 2025 |
| 317 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 318 | Samson Exploration LLC | Tulsa, OK 74101 | Oil & Gas Operator | Mar 2025 |
| 319 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 320 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 321 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2025 |
| 322 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 323 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 324 | Santa Fe Energy Oper. Part., LP | Houston, TX 77057 | Oil & Gas Operator | Dec 1994 |
| 325 | Saratoga Energy Corporation | Sourlake, TX 77659 | Oil & Gas Operator | Dec 2004 |
| 326 | Saratoga Oil Company | Batson, TX 77519 | Oil & Gas Operator | May 2025 |
| 327 | Saratoga Production Company LLC | Sourlake, TX 77659 | Oil Operator | May 2025 |
| 328 | Schmid Properties Inc | Hico, TX 76457 | Oil & Gas Operator | May 2025 |
| 329 | Se USA Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2009 |
| 330 | Seabreeze Production Co | Hungerford, TX 77448 | Oil & Gas Operator | May 2025 |
| 331 | Sedona Oil & Gas Corporation | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 332 | Seneca Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 333 | Serra Energy, Inc. | Hailey, ID 83333 | Oil & Gas Operator | May 2011 |
| 334 | Setab Prod. | Batson, TX 77519 | Oil & Gas Operator | May 2025 |
| 335 | Setex Oil And Gas Company | Houston, TX 77002 | Oil & Gas Operator | Feb 2012 |
| 336 | Setex Oil Company, L.P. | Houston, TX 77060 | Oil & Gas Operator | Jan 2000 |
| 337 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 338 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | May 2025 |
| 339 | Shoco Production LLC | Kilgore, TX 75663 | Oil & Gas Operator | May 2025 |
| 340 | Shoco Production, L.P. | Kilgore, TX 75663 | Oil & Gas Operator | May 2020 |
| 341 | Sideline Oil & Gas, L.P. | Friendswood, TX 77549 | Oil Operator | May 2025 |
| 342 | Silver Oak Energy, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2016 |
| 343 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Feb 2025 |
| 344 | Silverbrook Operating, LLC | Barker, TX 77413 | Oil Operator | May 2025 |
| 345 | Sizemore, James | Hardin, TX 77561 | Oil & Gas Operator | Jun 2003 |
| 346 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 347 | Slatex Well Service, Inc. | Batson, TX 77519 | Oil Operator | May 2025 |
| 348 | Smith Production Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 349 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 350 | Sonterra Oil & Gas, Inc. | Wichita, KS 67217 | Oil & Gas Operator | May 2025 |
| 351 | Southcoast Production Inc | Houston, TX 77010 | Oil & Gas Operator | May 2025 |
| 352 | Southern G Holdings, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2007 |
| 353 | Southern Oil Of Louisiana LLC | Madisonville, LA 70447 | Oil & Gas Operator | May 2025 |
| 354 | SSC, Inc. | Lubbock, TX 79408 | Oil & Gas Operator | May 2025 |
| 355 | Staghorn Resources, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2015 |
| 356 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 357 | Stillwater Petroleum Company | College Sta, TX 77845 | Oil & Gas Operator | Nov 1997 |
| 358 | Stone, M. L. | Kerrville, TX 78029 | Oil & Gas Operator | Aug 2003 |
| 359 | Sue-Ann Production Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 360 | Sulphur River Exploration, Inc. | Dallas, TX 75244 | Oil & Gas Operator | May 2025 |
| 361 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | May 2025 |
| 362 | Synergy Oil & Gas, L.P. | Houston, TX 77024 | Oil & Gas Operator | May 2012 |
| 363 | Tabco Exploration Inc. | New Orleans, LA 70131 | Oil & Gas Operator | Dec 1998 |
| 364 | Tandem Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 365 | Tema Oil And Gas Company | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 366 | Tema Oil And Gas, LLC | Houston, TX 77040 | Oil & Gas Operator | Apr 2000 |
| 367 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 368 | Texakota, Inc. | Houston, TX 77098 | Oil & Gas Operator | Mar 2021 |
| 369 | Texas American Resources Company | Austin, TX 78701 | Oil & Gas Operator | May 2025 |
| 370 | Texas Crude, Inc. | Houston, TX 77256 | Oil & Gas Operator | Oct 1995 |
| 371 | Texas Oil Company, The | Houston, TX 77018 | Oil & Gas Operator | Aug 2006 |
| 372 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 373 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 374 | Texian Operating Company, LLC | Irving, TX 75063 | Oil & Gas Operator | May 2025 |
| 375 | Titus Liberty Multi Well 2, LLC | Irving, TX 75063 | Oil & Gas Operator | May 2025 |
| 376 | TNT Oil Co. | Hamlin, TX 79520 | Oil & Gas Operator | May 2025 |
| 377 | Tomlinson, John Oil Operator | Batson, TX 77519 | Oil & Gas Operator | Mar 2008 |
| 378 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 379 | Trans-Pecos Resources, Inc. | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 380 | Transfuel Resources Co | Houston, TX 77215 | Oil & Gas Operator | Aug 2013 |
| 381 | Transoil, Inc. | Oklahoma City, OK 73129 | Oil & Gas Operator | May 2025 |
| 382 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |
| 383 | Trek Resources, Inc. | Dallas, TX 75207 | Oil & Gas Operator | May 2025 |
| 384 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 385 | Triangle Three Resources L.L.C. | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 386 | Triton Oil & Gas Corp. | Houston, TX 77002 | Oil & Gas Operator | Nov 2014 |
| 387 | True Oil Company | Casper, WY 82602 | Oil & Gas Operator | Aug 2003 |
| 388 | U. D. Man, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | May 2025 |
| 389 | U.S. Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 390 | Union Crude Operating Co. | Baytown, TX 77521 | Oil Operator | Aug 2003 |
| 391 | Union Gas Operating Company | Houston, TX 77014 | Oil & Gas Operator | May 2025 |
| 392 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 393 | Union Seaboard Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 394 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 395 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 396 | Universal Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2002 |
| 397 | Upstream Exploration LLC | Metairie, LA 70002 | Oil & Gas Operator | Jan 2020 |
| 398 | Vanya Oil & Gas, Inc. | Hardin, TX 77561 | Oil & Gas Operator | May 2025 |
| 399 | Ventex Operating Corp. | Addison, TX 75001 | Oil & Gas Operator | May 2025 |
| 400 | Venture 9 | Sourlake, TX 77659 | Oil & Gas Operator | Aug 2003 |