| 401 | Olsen Energy Inc. | Boerne, TX 78006 | Oil & Gas Operator | Apr 2025 |
| 402 | Opal Energy, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jun 2009 |
| 403 | Opex Energy, LLC | Houston, TX 77042 | Oil & Gas Operator | Mar 2008 |
| 404 | Osyka Permian, LLC | Houston, TX 77079 | Oil & Gas Operator | Apr 2025 |
| 405 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2025 |
| 406 | P&B Petroleum LLC | Miami, FL 33166 | Oil & Gas Operator | Apr 2025 |
| 407 | Pace Oil And Gas Company | Austin, TX 78715 | Oil & Gas Operator | Apr 2025 |
| 408 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | Apr 2025 |
| 409 | Pace West Production LC | San Angelo, TX 76904 | Oil & Gas Operator | Sep 1995 |
| 410 | Padon, Frank B. Oil Oper., Inc. | Houston, TX 77227 | Oil & Gas Operator | Nov 1998 |
| 411 | Paloma Operating, LLC | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 412 | Pantano Energy | San Antonio, TX 78258 | Oil & Gas Operator | Jul 1999 |
| 413 | Papco, Inc. | Warren, PA 16365 | Oil & Gas Operator | Apr 2025 |
| 414 | Parallel Petroleum Corporation | Midland, TX 79702 | Oil & Gas Operator | Jan 2010 |
| 415 | Parallel Petroleum LLC | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 416 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 417 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 418 | Patrick Pet. Corp. Of Michigan | Houston, TX 77227 | Oil & Gas Operator | Aug 1995 |
| 419 | Patterson Petroleum, Inc. | Snyder, TX 79550 | Oil & Gas Operator | Feb 2000 |
| 420 | Pax Energy LTD | Elmhurst, IL 60126 | Oil & Gas Operator | Dec 1998 |
| 421 | Payne, B.R. Oil & Gas, Inc. | Corpus Chrsti, TX 78411 | Oil & Gas Operator | Feb 2006 |
| 422 | Pearl, Bill H. Productions, Inc. | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Apr 2025 |
| 423 | Pegasus Operating, Inc. | Coldspring, TX 77331 | Oil & Gas Operator | Apr 2025 |
| 424 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 425 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 426 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 427 | Petro Vest, Inc. | Houston, TX 77046 | Oil & Gas Operator | Sep 2014 |
| 428 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 429 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 430 | Petro-Smith Operating LLC | Houston, TX 77010 | Oil & Gas Operator | Apr 2025 |
| 431 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Dec 2024 |
| 432 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 433 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Apr 2025 |
| 434 | Petroleum Resource Management Co | Fort Worth, TX 76107 | Oil & Gas Operator | Jan 2024 |
| 435 | PG&E Resources Offshore Company | Dallas, TX 75206 | Oil & Gas Operator | Oct 1994 |
| 436 | Phere Operating Inc | Spring Branch, TX 78070 | Oil & Gas Operator | Apr 2025 |
| 437 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 438 | Phoenix Fund, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2000 |
| 439 | Phylko Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | Aug 2003 |
| 440 | Pi Energy, Inc. | Wichita Falls, TX 76301 | Oil & Gas Operator | Apr 2025 |
| 441 | Pickens Company, Inc., The | Dallas, TX 75225 | Oil & Gas Operator | Jul 2024 |
| 442 | Pintail Oil & Gas, LLC | Midland, TX 79702 | Oil & Gas Operator | Dec 2019 |
| 443 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 444 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | Apr 2025 |
| 445 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 446 | Pitchfork Oil & Gas, Inc. | Orchard, TX 77464 | Oil & Gas Operator | Apr 2025 |
| 447 | Plains Marketing LP | Cushing, OK 74023 | Oil & Gas Operator | Dec 2022 |
| 448 | PPC Operating Company LLC | Houston, TX 77279 | Oil & Gas Operator | Jul 2019 |
| 449 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 450 | Premier Natural Resources, L.P. | Tulsa, OK 74105 | Oil & Gas Operator | Feb 2007 |
| 451 | Premier Natural Resources, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Apr 2025 |
| 452 | Presidio Exploration, Inc. | Englewood, CO 80155 | Oil & Gas Operator | May 1999 |
| 453 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2025 |
| 454 | Priest Petroleum Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 455 | Princess Three Operating, LLC | Henderson, TX 75653 | Oil & Gas Operator | Apr 2025 |
| 456 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 457 | Progenies Operating LLC | Austin, TX 78746 | Oil & Gas Operator | Apr 2025 |
| 458 | Projj Energy LLC | Sugar Land, TX 77496 | Oil & Gas Operator | Apr 2025 |
| 459 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2025 |
| 460 | Prolithic Energy Company, L.P. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Aug 2002 |
| 461 | Pure Resources, L.P. | Midland, TX 79701 | Oil & Gas Operator | Mar 2006 |
| 462 | Pyle Petroleum, Inc. | Tyler, TX 75703 | Oil & Gas Operator | Apr 2025 |
| 463 | Pyramid Exploration | Houston, TX 77241 | Oil & Gas Operator | Sep 1995 |
| 464 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Jan 2025 |
| 465 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 466 | Quisto Energy Corp. | Kerrville, TX 78029 | Oil & Gas Operator | Jan 1998 |
| 467 | Ramsey Production Company, LLC | Austin, TX 78766 | Oil & Gas Operator | Jan 2017 |
| 468 | Remora Management, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Apr 2025 |
| 469 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 470 | Renuergy LLC | Houston, TX 77024 | Oil & Gas Operator | Jan 2024 |
| 471 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | Apr 2025 |
| 472 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | Apr 2025 |
| 473 | Resource Expl & Prod, Inc. | Salado, TX 76571 | Oil & Gas Operator | Apr 2025 |
| 474 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |
| 475 | Richardson, Marshall T. | Midfield, TX 77458 | Oil & Gas Operator | Apr 2025 |
| 476 | Richman Petroleum Corp. | Grapevine, TX 76051 | Oil & Gas Operator | Jul 2006 |
| 477 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Apr 2025 |
| 478 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 479 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 480 | Riseden Services, Inc. | Houston, TX 77256 | Oil & Gas Operator | Sep 1997 |
| 481 | Roca Production, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Apr 2025 |
| 482 | Rocinante | Houston, TX 77058 | Oil Operator | Apr 2025 |
| 483 | Rock Resources, Inc. | Corpus Chrsti, TX 78414 | Oil & Gas Operator | Apr 2025 |
| 484 | Rodel Oil & Gas Company | Houston, TX 77218 | Oil & Gas Operator | Apr 2025 |
| 485 | Rodessa Management, Inc. | Longview, TX 75606 | Oil & Gas Operator | May 1995 |
| 486 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Apr 2025 |
| 487 | Roland Carlson LLC | Austin, TX 78705 | Gas Operator | Apr 2025 |
| 488 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 489 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | Apr 2025 |
| 490 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 491 | Royalty Land & Dev. Co., Inc. | Wolfforth, TX 79382 | Oil & Gas Operator | Apr 2025 |
| 492 | RPM Operating Company | New Braunfels, TX 78131 | Oil & Gas Operator | Mar 2008 |
| 493 | Rwa, LLC | Boyd, TX 76023 | Oil & Gas Operator | Apr 2025 |
| 494 | Sabinal Resources, Inc. | Kingwood, TX 77339 | Oil & Gas Operator | Apr 2025 |
| 495 | Salvador Oil, LLC | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 496 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 497 | Samson Contour Energy E&P, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Sep 2017 |
| 498 | Samson Exploration LLC | Tulsa, OK 74101 | Oil & Gas Operator | Feb 2025 |
| 499 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 500 | Samson Lone Star, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |