| 401 | Nog Production & Operating LLC | Goliad, TX 77963 | Oil & Gas Operator | Apr 2025 |
| 402 | North American Royalties, Inc. | Chattanooga, TN 37408 | Oil & Gas Operator | Oct 2001 |
| 403 | North Central Oil Corp. | Houston, TX 77252 | Oil & Gas Operator | Dec 2005 |
| 404 | Null, W.M. Operations, Inc. | Corpus Chrsti, TX 78475 | Oil & Gas Operator | Jun 2002 |
| 405 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 406 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2025 |
| 407 | Okie Operating Company, LTD. | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 408 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | Apr 2025 |
| 409 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | Apr 2025 |
| 410 | Origin Production Group LLC | Luling, TX 78648 | Oil Operator | Apr 2025 |
| 411 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 412 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2025 |
| 413 | Overton Park Oil & Gas LP | Fort Worth, TX 76109 | Oil & Gas Operator | Apr 2025 |
| 414 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 415 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 416 | P1 Energy, LLC | Judson, TX 75660 | Oil & Gas Operator | Apr 2025 |
| 417 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | Apr 2025 |
| 418 | Pace West Production LC | San Angelo, TX 76904 | Oil & Gas Operator | Sep 1995 |
| 419 | Pantano Energy | San Antonio, TX 78258 | Oil & Gas Operator | Jul 1999 |
| 420 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 421 | Paragon Energy, Inc. | Dallas, TX 75244 | Oil & Gas Operator | Apr 2025 |
| 422 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 423 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 424 | Patriot Operating Company, Inc. | Houston, TX 77008 | Oil & Gas Operator | Sep 2003 |
| 425 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | Apr 2025 |
| 426 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 427 | Patterson Petroleum, Inc. | Snyder, TX 79550 | Oil & Gas Operator | Feb 2000 |
| 428 | Patton Oil Corp. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Aug 2003 |
| 429 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 430 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 431 | Permian Solutions LLC | Midland, TX 79702 | Oil Operator | Apr 2025 |
| 432 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 433 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 434 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 435 | Petrocorp Acquisition Company | Tulsa, OK 74121 | Oil & Gas Operator | Dec 2002 |
| 436 | Petrocorp Incorporated,A TX.Corp | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2005 |
| 437 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Dec 2024 |
| 438 | Petrogas Operating Corporation | Garland, TX 75043 | Oil Operator | Feb 2010 |
| 439 | Petroglyph Operating Co | Boise, ID 83709 | Oil & Gas Operator | Jul 2017 |
| 440 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 441 | Petroleum Resource Management Co | Fort Worth, TX 76107 | Oil & Gas Operator | Jan 2024 |
| 442 | Petropro Energy Partners, L.P. | Houston, TX 77024 | Oil & Gas Operator | Jan 2013 |
| 443 | PG&E Resources Company | Houston, TX 77042 | Oil & Gas Operator | May 1995 |
| 444 | PH Exploration, Inc. | Houston, TX 77008 | Oil & Gas Operator | Nov 2001 |
| 445 | Phillips 66 Company | Bartlesville, OK 74004 | Oil & Gas Operator | Aug 1997 |
| 446 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 447 | Phoenix Fund, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2000 |
| 448 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 449 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | Apr 2025 |
| 450 | Pitchfork Oil & Gas, Inc. | Orchard, TX 77464 | Oil & Gas Operator | Apr 2025 |
| 451 | Placer Oil Co. | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2008 |
| 452 | Plains Exploration & Prod. Co. | Houston, TX 77002 | Oil & Gas Operator | Jul 2013 |
| 453 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 454 | Pmo | Garland, TX 75040 | Oil & Gas Operator | Feb 2018 |
| 455 | Pool Operating Corporation | Lago VIsta, TX 78645 | Oil & Gas Operator | Oct 2016 |
| 456 | Prairie Petroleum, Inc | Plano, TX 75093 | Oil & Gas Operator | May 1999 |
| 457 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 458 | Prevail Energy, Inc | Corpus Chrsti, TX 78469 | Oil & Gas Operator | Apr 2025 |
| 459 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2025 |
| 460 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 461 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 462 | Proco Operating Co., Inc. | Graford, TX 76449 | Oil & Gas Operator | Apr 2025 |
| 463 | Proex Energy Management, L.L.C. | Spring, TX 77386 | Oil & Gas Operator | Apr 2025 |
| 464 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2025 |
| 465 | Property Development Group, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Apr 2025 |
| 466 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Jan 2025 |
| 467 | Quest Research & Dev. Corp. | Weatherford, TX 76086 | Oil & Gas Operator | Apr 2025 |
| 468 | R & B Energy, LLC | Shelby, MT 59474 | Oil Operator | Oct 2024 |
| 469 | R & S Energy Company | Luling, TX 78648 | Oil & Gas Operator | Dec 2010 |
| 470 | R & S Oil Production Co. | Luling, TX 78648 | Oil & Gas Operator | Apr 2025 |
| 471 | Ragars Oil & Gas Co. | Austin, TX 78716 | Oil & Gas Operator | Apr 2025 |
| 472 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | Apr 2025 |
| 473 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 474 | Ranger Oil Company | Canada, 00100 | Oil & Gas Operator | Sep 2001 |
| 475 | Reach Oil And Gas Company Inc | Oklahoma City, OK 73118-1100 | Oil & Gas Operator | Jan 2025 |
| 476 | Red Shell Inc | Dale, TX 78616 | Oil & Gas Operator | Apr 2025 |
| 477 | Red Wolf Oil Company, Inc. | Brenham, TX 77833 | Oil & Gas Operator | Apr 2025 |
| 478 | Redwood Operating, Inc. | Houston, TX 77058 | Oil & Gas Operator | Apr 2025 |
| 479 | Remora Management, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Apr 2025 |
| 480 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 481 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | Apr 2025 |
| 482 | Repsol Oil & Gas USA, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | Apr 2025 |
| 483 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | Apr 2025 |
| 484 | Riddle Engineering Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 485 | Riggs, Don R. | San Antonio, TX 78270 | Oil & Gas Operator | Aug 2003 |
| 486 | Riley Exploration Opg Co, LLC | La Grange, TX 78945 | Oil & Gas Operator | Apr 2025 |
| 487 | Riley Exploration, LLC | Blanchard, OK 73010 | Oil & Gas Operator | Apr 2025 |
| 488 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Apr 2025 |
| 489 | Rio Bravo Expl. & Prod. Co. | Houston, TX 77055 | Oil & Gas Operator | Apr 2020 |
| 490 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 491 | Robertson Resources, Inc. | Midland, TX 79708 | Oil & Gas Operator | Apr 2025 |
| 492 | Rocc Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Apr 2024 |
| 493 | Rocc Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | Apr 2025 |
| 494 | Rocker A Operating Company | Post, TX 79356 | Oil & Gas Operator | Aug 2022 |
| 495 | Rockoil Energy Of Texas, Inc. | Weatherford, TX 76086 | Oil & Gas Operator | Apr 2025 |
| 496 | Rocky Creek Resources, LLC | Houston, TX 77055 | Oil & Gas Operator | Apr 2025 |
| 497 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 498 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | Apr 2025 |
| 499 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 500 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |