| 301 | R&R Resources Corporation | Houston, TX 77056 | Oil & Gas Operator | Dec 2015 |
| 302 | Ramrod Oil And Gas (U.S.A.) Inc. | Corpus Chrsti, TX 78403 | Oil & Gas Operator | May 2025 |
| 303 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | May 2025 |
| 304 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 305 | Rathburn Land & Devel, Inc. | Giddings, TX 78942 | Oil & Gas Operator | Aug 2003 |
| 306 | Rci, L.L.C. | Abilene, TX 79606 | Oil & Gas Operator | May 2025 |
| 307 | Red River Oil & Gas LLC | Cherry Hills, CO 80110 | Oil & Gas Operator | Feb 2025 |
| 308 | Red Water Resources, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | May 2025 |
| 309 | Redbud E & P, Inc. | Spring, TX 77379 | Oil & Gas Operator | May 2025 |
| 310 | Redstone Operating, Inc. | Austin, TX 78734 | Oil & Gas Operator | Jan 2015 |
| 311 | Redwood Energy, Inc. | Giddings, TX 78942 | Oil & Gas Operator | Jul 1997 |
| 312 | Reserve Production, Inc. | Tyler, TX 75713 | Oil & Gas Operator | Mar 2008 |
| 313 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |
| 314 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 315 | Ro-Jo, Inc. | Highland VLG, TX 75077 | Oil & Gas Operator | Aug 2003 |
| 316 | Rocc Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 317 | Rockbridge Oil & Gas | Houston, TX 77027 | Oil & Gas Operator | Mar 1990 |
| 318 | Rockford Energy Partners II, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2007 |
| 319 | Rockford Energy Partners III,LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2012 |
| 320 | Rockford Panhandle, LLC | Tulsa, OK 74105 | Oil & Gas Operator | Sep 2008 |
| 321 | Rodel Oil & Gas Company | Houston, TX 77218 | Oil & Gas Operator | May 2025 |
| 322 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 323 | Rwa Corporation | Houston, TX 77024 | Oil & Gas Operator | Sep 1999 |
| 324 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 325 | Sabalo Exploration Operating,LLC | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Jan 2021 |
| 326 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | May 2025 |
| 327 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 328 | San Dia Producing Company | Deanville, TX 77852 | Oil & Gas Operator | May 2025 |
| 329 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 330 | Sandel Energy, Inc. | Huntsville, TX 77342 | Oil & Gas Operator | Apr 2004 |
| 331 | Sandel Operating Company | Huntsville, TX 77340 | Oil & Gas Operator | May 2025 |
| 332 | Seguro Well Service, Inc. | Gonzales, TX 78629 | Oil & Gas Operator | May 2025 |
| 333 | Seneca Resources Co LLC | Cranberry Township, PA 16066 | Oil & Gas Operator | Mar 2025 |
| 334 | Seneca Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 335 | Senora Resources, Inc. | Dime Box, TX 77853 | Oil & Gas Operator | May 2025 |
| 336 | Sequoia Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Nov 2009 |
| 337 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | May 2025 |
| 338 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | May 2025 |
| 339 | Shield Petroleum | College Sta, TX 77845 | Oil & Gas Operator | May 2025 |
| 340 | Shoreham Oil & Gas Company, Inc. | Katy, TX 77492 | Oil & Gas Operator | May 2025 |
| 341 | Showdown Operating, Inc. | Dallas, TX 75230 | Oil & Gas Operator | May 1996 |
| 342 | Silver Creek Oil & Gas, LLC | Flower Mound, TX 75022 | Oil & Gas Operator | May 2025 |
| 343 | Silver Creek Resources, LLC | Irving, TX 75038 | Oil & Gas Operator | Apr 2017 |
| 344 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 345 | Smith Petroleum Company | Spring, TX 77389 | Oil & Gas Operator | May 2025 |
| 346 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 347 | South Texas Operating Company | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 348 | Southern Bay Operating, L.L.C. | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 349 | Southwest Resources, Inc. | Brenham, TX 77834 | Oil & Gas Operator | May 2025 |
| 350 | Square One Corporation | Giddings, TX 78942 | Oil & Gas Operator | Dec 2012 |
| 351 | SSC, Inc. | Lubbock, TX 79408 | Oil & Gas Operator | May 2025 |
| 352 | Stanton Mineral Development Inc | Austin, TX 78759 | Oil & Gas Operator | May 2025 |
| 353 | Steller Energy & Investment Corp | Plano, TX 75093 | Oil & Gas Operator | Feb 2021 |
| 354 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | May 2025 |
| 355 | Stephens, Autry C. | Midland, TX 79701 | Oil & Gas Operator | Mar 2023 |
| 356 | Stillwater Petroleum Company | College Sta, TX 77845 | Oil & Gas Operator | Nov 1997 |
| 357 | Sto Operating Company | San Antonio, TX 78258 | Oil & Gas Operator | May 2025 |
| 358 | Stratlynn, Inc. | Conroe, TX 77305 | Oil & Gas Operator | Mar 2008 |
| 359 | Stroud Energy, LTD. | Fort Worth, TX 76102 | Oil & Gas Operator | Jun 2006 |
| 360 | Stroud Oil Properties, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | May 2013 |
| 361 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | May 2025 |
| 362 | SW Operating, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Sep 2000 |
| 363 | T & T Production Co. | Victoria, TX 77902 | Oil & Gas Operator | Feb 1995 |
| 364 | Tandem Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 365 | TC3 Energy Services Company | Bryan, TX 77805 | Oil & Gas Operator | Jan 2005 |
| 366 | TDC Engineering, Inc. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 367 | Te-Ray Resources, Inc. | Oklahoma City, OK 73108 | Oil & Gas Operator | Mar 2015 |
| 368 | Te-Ray Resources, LLC | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2025 |
| 369 | Tekna Synergy Corporation | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 370 | Tempo Energy, Inc. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 371 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | May 2025 |
| 372 | Texakoma Oil & Gas Corp | Dallas, TX 75240 | Oil & Gas Operator | Sep 2014 |
| 373 | Texas Onshore Energy, Inc. | Austin, TX 78704 | Oil & Gas Operator | May 2025 |
| 374 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 375 | Texas Refining, Inc. | Houston, TX 77057 | Oil & Gas Operator | Aug 2003 |
| 376 | Texas Royalty Corp. | Austin, TX 78746 | Oil & Gas Operator | May 2025 |
| 377 | Texas State Oil Co. | Irving, TX 75062 | Oil & Gas Operator | Mar 2017 |
| 378 | Texcal Energy (GP) LLC | Denver, CO 80202 | Oil & Gas Operator | Mar 2016 |
| 379 | Texron Operating, LLC | Bulverde, TX 78163 | Oil & Gas Operator | May 2025 |
| 380 | Torch Energy Services, Inc. | Houston, TX 77010 | Oil & Gas Operator | Sep 2011 |
| 381 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 382 | Tower Resources Inc | Conroe, TX 77304 | Oil & Gas Operator | May 2025 |
| 383 | Trailblazer Energy Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | May 2025 |
| 384 | Trestle Creek Properties, LLC | Manchaca, TX 78652 | Oil & Gas Operator | May 2025 |
| 385 | Tri-Union Development Corp. | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 386 | Tripp Oil Company Inc | Houston, TX 77023 | Oil & Gas Operator | Jan 1992 |
| 387 | Tularosa Operating Company | Kerrville, TX 78029 | Oil & Gas Operator | Mar 2024 |
| 388 | Twojo, Inc. | Longview, TX 75601 | Oil & Gas Operator | Nov 1996 |
| 389 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 390 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 391 | United Oil & Minerals L. P. | Austin, TX 78746 | Oil & Gas Operator | Jun 2003 |
| 392 | United Oil & Minerals, Inc. | Austin, TX 78746 | Oil & Gas Operator | Jan 2001 |
| 393 | United Resources LP | Austin, TX 78746 | Oil & Gas Operator | Oct 2011 |
| 394 | Vaalco Energy (USA), Inc. | Houston, TX 77042 | Oil & Gas Operator | Dec 2016 |
| 395 | Vanco Oil & Gas Corp. | Abilene, TX 79604 | Oil & Gas Operator | May 2025 |
| 396 | Verdun Oil & Gas LLC | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 397 | Vess Oil Corporation | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 398 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Feb 2025 |
| 399 | Viola Production Inc | Dallas, TX 75251 | Oil & Gas Operator | May 2025 |
| 400 | Vista Resources, Inc. (A) | Midland, TX 79701 | Oil & Gas Operator | Feb 2000 |