| 401 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 402 | Pittencrieff (Gulf Coast), Inc. | Abilene, TX 79608 | Oil & Gas Operator | Sep 1998 |
| 403 | Pittencrieff America Inc | Abilene, TX 79608 | Oil & Gas Operator | Feb 2003 |
| 404 | Placer Oil Co. | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2008 |
| 405 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 406 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Feb 2026 |
| 407 | Preferred Pipeline Corp. | Victoria, TX 77902 | Oil & Gas Operator | Dec 2025 |
| 408 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2026 |
| 409 | Prevail Energy, Inc | Corpus Chrsti, TX 78469 | Oil & Gas Operator | Feb 2026 |
| 410 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2026 |
| 411 | Princess Three Corporation | Henderson, TX 75653 | Oil & Gas Operator | Apr 2020 |
| 412 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 413 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Feb 2026 |
| 414 | QNK Energy,Inc. | Alice, TX 78333 | Oil & Gas Operator | Aug 2016 |
| 415 | Quatro Oil And Gas, Inc. | Joshua, TX 76058 | Oil & Gas Operator | Feb 2026 |
| 416 | Quorum Energy Company | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 417 | R.C.I. Energy | Alice, TX 78333 | Oil & Gas Operator | Feb 2026 |
| 418 | Rana Energy Company | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 419 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 420 | Rawhide Operating, Inc. | New Braunfels, TX 78131 | Oil & Gas Operator | Feb 2026 |
| 421 | Redfish Bay Operating Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Apr 1998 |
| 422 | Redmon Oil Company, Inc., The | Plano, TX 75023 | Oil & Gas Operator | Feb 2026 |
| 423 | Redwine Resources Inc | Dallas, TX 75225 | Oil & Gas Operator | Feb 2015 |
| 424 | Reef Exploration, Inc. (A-1) | Richardson, TX 75080 | Oil & Gas Operator | Oct 2006 |
| 425 | Reef Exploration, L.P. | Richardson, TX 75080 | Oil & Gas Operator | Feb 2026 |
| 426 | Reh Energy, Inc. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Feb 2026 |
| 427 | Reichmann Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Feb 2026 |
| 428 | Reliance Energy, Inc. | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 429 | Reliance Operating Company | Midland, TX 79702 | Oil & Gas Operator | Feb 2000 |
| 430 | Republic Resources, LLC. | San Antonio, TX 78212 | Oil & Gas Operator | Feb 2026 |
| 431 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | Feb 2026 |
| 432 | Resource Expl & Prod, Inc. | Salado, TX 76571 | Oil & Gas Operator | Feb 2026 |
| 433 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 434 | Ridgeway Exco, Inc. | San Antonio, TX 78279 | Oil & Gas Operator | Mar 1996 |
| 435 | Riggins Energy Inc. | Vernon, TX 76385 | Oil & Gas Operator | Jul 2004 |
| 436 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Feb 2026 |
| 437 | Rising Star Energy, L.L.C. | Dallas, TX 75219 | Oil & Gas Operator | Aug 2006 |
| 438 | Rlu Operating, LLC | Devine, TX 78016 | Oil & Gas Operator | Feb 2026 |
| 439 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 440 | Robison, J. H. & Assoc. LTD. | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 1996 |
| 441 | Rocanville Corporation | Dallas, TX 75225 | Oil & Gas Operator | Dec 2016 |
| 442 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Feb 2026 |
| 443 | Romack Production Company | Granville, OH 43023 | Oil Operator | Mar 2018 |
| 444 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 445 | Royal Production Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Feb 2026 |
| 446 | Rudman Partnership, The | Dallas, TX 75201 | Oil & Gas Operator | Dec 2014 |
| 447 | RWJ Operating LLC | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 448 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 449 | S N D Energy Company, Inc. | Kilgore, TX 75662 | Oil & Gas Operator | Feb 2026 |
| 450 | Sabco Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2011 |
| 451 | Sabco Operating Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2018 |
| 452 | Salvador Oil, LLC | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 453 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 454 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2025 |
| 455 | Samurai Operating Co. L.L.C. | Dayton, TX 77535 | Oil & Gas Operator | Feb 2026 |
| 456 | San Patricio Corporation | Dinero, TX 78350 | Oil & Gas Operator | Sep 2003 |
| 457 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 458 | Sandia Operating Corp. | San Antonio, TX 78270 | Oil & Gas Operator | May 2010 |
| 459 | Santa Rosa Operating, LLC | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Feb 2026 |
| 460 | Sarita Energy Resources, LTD. | Houston, TX 77277 | Oil & Gas Operator | Feb 2026 |
| 461 | Satex Energy, Inc. | San Antonio, TX 78216 | Oil & Gas Operator | Aug 2003 |
| 462 | Savage Exploration, Inc. | San Marcos, TX 78666 | Oil & Gas Operator | Feb 2026 |
| 463 | Scythian, LTD. | Midland, TX 79701 | Oil & Gas Operator | Dec 2020 |
| 464 | Shana Petroleum Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2002 |
| 465 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 466 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Feb 2026 |
| 467 | Shoco Production LLC | Kilgore, TX 75663 | Oil & Gas Operator | Feb 2026 |
| 468 | Shoreline Production Serv., Inc. | Rockport, TX 78381 | Oil & Gas Operator | Apr 2002 |
| 469 | Silver Fox Oil & Gas LLC | McAllen, TX 78504 | Oil & Gas Operator | Feb 2026 |
| 470 | Situs Oil & Gas, LLC | Corpus Chrsti, TX 78414 | Oil Operator | Feb 2026 |
| 471 | Smith Petroleum Company | Spring, TX 77389 | Oil & Gas Operator | Feb 2026 |
| 472 | South Central Texas Oil & Gas Co | Houston, TX 77060 | Oil & Gas Operator | Feb 2026 |
| 473 | South Leeville, LLC | Houston, TX 77069 | Oil & Gas Operator | Oct 2022 |
| 474 | Southcoast Production Inc | Houston, TX 77010 | Oil & Gas Operator | Feb 2026 |
| 475 | Southern Resource Company | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Mar 2022 |
| 476 | Southern Royalty Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Feb 1997 |
| 477 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 478 | Southwest Gathering Company | Alice, TX 78332 | Oil & Gas Operator | Feb 2026 |
| 479 | Southwestern Energy Prod Co | Houston, TX 77032 | Oil & Gas Operator | Jun 2015 |
| 480 | Star Production, Inc. | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 481 | Starco Exploration, Inc. | Dallas, TX 75360 | Oil & Gas Operator | Feb 2026 |
| 482 | Startex Energy, Inc. | Abilene, TX 79608 | Oil & Gas Operator | Feb 2026 |
| 483 | Stephens & Johnson Operating Co. | Wichita Falls, TX 76307 | Oil & Gas Operator | Feb 2026 |
| 484 | Striper Oil, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Apr 2002 |
| 485 | STS Petroleum LLC | Houston, TX 77289 | Oil & Gas Operator | Feb 2026 |
| 486 | Sue-Ann Operating, L.C. | Victoria, TX 77903 | Oil & Gas Operator | Feb 2026 |
| 487 | Sue-Ann Production Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 488 | Suemaur Expl. & Prod., LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jun 2024 |
| 489 | Suemaur Exploration, Inc. | Corpus Chrsti, TX 78470 | Oil & Gas Operator | Mar 2008 |
| 490 | Suemaur Operating LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Feb 2026 |
| 491 | Sulphur River Exploration, Inc. | Dallas, TX 75244 | Oil & Gas Operator | Feb 2026 |
| 492 | Summit Resources, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2016 |
| 493 | Sun Exploration, Inc. | Alice, TX 78333 | Oil & Gas Operator | Feb 2026 |
| 494 | Sure Flow Oil & Gas, Inc. | Victoria, TX 77902 | Oil & Gas Operator | Feb 2026 |
| 495 | Synergy Oil & Gas, Inc. (A) | Houston, TX 77024 | Oil & Gas Operator | Aug 2001 |
| 496 | Synergy Production Company | Houston, TX 77024 | Oil & Gas Operator | Jan 1996 |
| 497 | T.O.I. | Midland, TX 79710 | Oil & Gas Operator | Mar 2001 |
| 498 | Tag Operating Company, Inc. | Houston, TX 77092 | Oil & Gas Operator | Feb 2026 |
| 499 | Tallgrass Energy, L.L.C. | Tulsa, OK 74136 | Oil & Gas Operator | Feb 2026 |
| 500 | Tamarack Petroleum Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |