| 301 | Rancho Blanco Corporation | San Antonio, TX 78205 | Oil & Gas Operator | Apr 1995 |
| 302 | Ray Jr. Co., Inc. | Pleasanton, TX 78064 | Oil & Gas Operator | Jul 2025 |
| 303 | Reef Exploration, L.P. | Richardson, TX 75080 | Oil & Gas Operator | Jul 2025 |
| 304 | Reichmann Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2025 |
| 305 | Remco Oil & Gas Production,Inc. | Rio Grande Ci, TX 78582 | Oil & Gas Operator | Nov 2021 |
| 306 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 307 | Ress Production Co. | Farmington, NM 87499 | Oil & Gas Operator | Jul 2025 |
| 308 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 309 | Ricochet Energy, Inc. | San Antonio, TX 78258 | Oil & Gas Operator | Jul 2025 |
| 310 | Ridgeline Energy Inc. | Miami, FL 33130 | Oil & Gas Operator | Jul 2025 |
| 311 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 312 | Rio Grande Drilling Company | San Antonio, TX 78212 | Oil & Gas Operator | Dec 1999 |
| 313 | Rlu Operating, LLC | Devine, TX 78016 | Oil & Gas Operator | Jul 2025 |
| 314 | RMB Operating LLC | Lubbock, TX 79493 | Oil & Gas Operator | Jul 2025 |
| 315 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 316 | RMR Operating, LLC | Plano, TX 75024 | Oil & Gas Operator | Jul 2025 |
| 317 | RMX Oil & Gas, LLC | Zapata, TX 78076 | Oil Operator | Jul 2025 |
| 318 | Rockdale Energy, LLC | Houston, TX 77024 | Oil & Gas Operator | Dec 2020 |
| 319 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | Jul 2025 |
| 320 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 321 | Rudman Partnership, The | Dallas, TX 75201 | Oil & Gas Operator | Dec 2014 |
| 322 | S M K Energy Corporation | Corpus Chrsti, TX 78475 | Oil & Gas Operator | Jul 2025 |
| 323 | Safari Production Company, Inc. | McAllen, TX 78501 | Oil & Gas Operator | Jul 2025 |
| 324 | Salt Creek Production, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | Jul 2025 |
| 325 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 326 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 327 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 328 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2025 |
| 329 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 330 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 331 | Sandel Operating Company | Huntsville, TX 77340 | Oil & Gas Operator | Jul 2025 |
| 332 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 333 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | Jul 2025 |
| 334 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 335 | Sheridan Energy,Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 336 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Jul 2025 |
| 337 | Silver Fox Oil & Gas LLC | McAllen, TX 78504 | Oil & Gas Operator | Jul 2025 |
| 338 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Apr 2025 |
| 339 | Smith Operating And MGMT Co. | Shreveport, LA 71161 | Oil & Gas Operator | Jun 2023 |
| 340 | Smith Production Inc. | The Woodlands, TX 77381 | Oil & Gas Operator | Jul 2025 |
| 341 | Sonat Exploration Co. - Houston | Houston, TX 77251 | Oil & Gas Operator | Dec 1999 |
| 342 | Sonat Exploration Company -Tyler | Houston, TX 77251 | Oil & Gas Operator | Dec 1999 |
| 343 | Southern G Holdings, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2007 |
| 344 | Southern Tejas Asset Group LLC | McAllen, TX 78501 | Oil & Gas Operator | Jul 2025 |
| 345 | Southwest Land & Minerals, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Aug 2003 |
| 346 | Spirit Energy L.L.C. | Caddo Mills, TX 75135 | Oil & Gas Operator | Dec 2018 |
| 347 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Jul 2025 |
| 348 | Stivers Inc | Graham, TX 76450 | Oil & Gas Operator | May 2003 |
| 349 | Sue-Ann Operating, L.C. | Victoria, TX 77903 | Oil & Gas Operator | Jul 2025 |
| 350 | Suemaur Expl. & Prod., LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2024 |
| 351 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 352 | Synergy Oil & Gas, L.P. | Houston, TX 77024 | Oil & Gas Operator | May 2012 |
| 353 | Synthetic Energy Corporation | Houston, TX 77006 | Oil Operator | Jul 2025 |
| 354 | Tag Operating Company, Inc. | Houston, TX 77092 | Oil & Gas Operator | Jul 2025 |
| 355 | TD Natural Resources LLC | Cuero, TX 77954 | Oil & Gas Operator | Jul 2025 |
| 356 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Jul 2025 |
| 357 | Tejas Gas Pipeline, L.P. | Houston, TX 77002 | Oil & Gas Operator | Feb 2002 |
| 358 | Tepee Petroleum Company, Inc. | Houston, TX 77098 | Oil & Gas Operator | Feb 2014 |
| 359 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 360 | Tesoro Expl. & Prod. Company | San Antonio, TX 78216 | Gas Operator | Sep 2010 |
| 361 | Texana Operating Company | Houston, TX 77090 | Oil & Gas Operator | Jul 2025 |
| 362 | Texas Southern Petroleum Corp. | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 363 | Texas, Les & Co. | Austin, TX 78746 | Oil & Gas Operator | Jul 2025 |
| 364 | Texas, Les C., LTD. | Houston, TX 77095 | Oil & Gas Operator | Dec 2006 |
| 365 | Thorp Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2014 |
| 366 | Three C Exploration, LLC | Hebbronville, TX 78361 | Oil & Gas Operator | Jul 2025 |
| 367 | Three-C Oil And Gas | Hebbronville, TX 78361 | Oil & Gas Operator | Jul 2025 |
| 368 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 369 | Transamerican Natural Gas Corp. | Houston, TX 77032 | Oil & Gas Operator | Aug 2000 |
| 370 | Transpacific Energy, LLC | Katy, TX 77450 | Oil & Gas Operator | Jul 2025 |
| 371 | Transtexas Gas Corporation | Houston, TX 77265 | Oil & Gas Operator | Aug 2005 |
| 372 | Traton Operating Company | Kingwood, TX 77339 | Oil & Gas Operator | Mar 2019 |
| 373 | Tri-C Resources, Inc. | Houston, TX 77024 | Oil & Gas Operator | Aug 2009 |
| 374 | Trinity River Energy Oper, LLC | Houston, TX 77008 | Oil & Gas Operator | May 2018 |
| 375 | U.S. Enercorp, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2004 |
| 376 | U.S. Enercorp, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 2019 |
| 377 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 378 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2025 |
| 379 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 380 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 381 | Vantage Operating II, LLC | San Antonio, TX 78230 | Oil & Gas Operator | Jul 2025 |
| 382 | Vantage Operating, LLC | San Antonio, TX 78230 | Oil & Gas Operator | Jul 2025 |
| 383 | Vaquero Operating | FT Stockton, TX 79735 | Oil & Gas Operator | Jul 2025 |
| 384 | Varas Energy Operating Company, LLC | Houston, TX 77005 | Oil & Gas Operator | Jul 2025 |
| 385 | Vast Oil TX Operating LLC | Fullerton, CA 92832 | Oil & Gas Operator | Jul 2025 |
| 386 | Ventum Oil And Gas, LP | Northbrook, IL 60062 | Oil & Gas Operator | Mar 2010 |
| 387 | Vision Oil And Gas LLC | Laredo, TX 78041 | Oil & Gas Operator | Jul 2025 |
| 388 | Wadi Petroleum Inc | Houston, TX 77014 | Oil & Gas Operator | May 2018 |
| 389 | Wagner & Brown, LTD. | Midland, TX 79702 | Oil & Gas Operator | Aug 2014 |
| 390 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2025 |
| 391 | Wagner, Duer & Co. | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 1999 |
| 392 | Waters Eng. & Operating, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Sep 2013 |
| 393 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 394 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Jul 2025 |
| 395 | Whitson, James A., Jr. | Houston, TX 77063 | Oil & Gas Operator | Nov 2011 |
| 396 | Whittington Operating Company | Houston, TX 77069 | Oil & Gas Operator | Jul 2025 |
| 397 | Windrush Operating Co., L.L.C. | Longville, LA 70652 | Oil & Gas Operator | Jul 2025 |
| 398 | World Energy Corporation | Laredo, TX 78041 | Oil & Gas Operator | Aug 2003 |
| 399 | Wright Brothers Energy, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Jul 2025 |
| 400 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |