| 401 | Olipdp II, LLC | Lafayette, LA 70503 | Oil & Gas Operator | May 2025 |
| 402 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | May 2025 |
| 403 | Origin Production Group LLC | Luling, TX 78648 | Oil Operator | May 2025 |
| 404 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 405 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | May 2025 |
| 406 | Overton Park Oil & Gas LP | Fort Worth, TX 76109 | Oil & Gas Operator | May 2025 |
| 407 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 408 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 409 | P1 Energy, LLC | Judson, TX 75660 | Oil & Gas Operator | May 2025 |
| 410 | Pace Production Co. | San Angelo, TX 76902 | Oil & Gas Operator | May 2025 |
| 411 | Pace West Production LC | San Angelo, TX 76904 | Oil & Gas Operator | Sep 1995 |
| 412 | Pantano Energy | San Antonio, TX 78258 | Oil & Gas Operator | Jul 1999 |
| 413 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 414 | Paragon Energy, Inc. | Dallas, TX 75244 | Oil & Gas Operator | May 2025 |
| 415 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 416 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 417 | Patriot Operating Company, Inc. | Houston, TX 77008 | Oil & Gas Operator | Sep 2003 |
| 418 | Patterson Energy Corporation | Dallas, TX 75205 | Oil & Gas Operator | May 2025 |
| 419 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 420 | Patterson Petroleum, Inc. | Snyder, TX 79550 | Oil & Gas Operator | Feb 2000 |
| 421 | Patton Oil Corp. | Corpus Chrsti, TX 78466 | Oil & Gas Operator | Aug 2003 |
| 422 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 423 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 424 | Permian Solutions LLC | Midland, TX 79702 | Oil Operator | May 2025 |
| 425 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | May 2025 |
| 426 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 427 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 428 | Petrocorp Acquisition Company | Tulsa, OK 74121 | Oil & Gas Operator | Dec 2002 |
| 429 | Petrocorp Incorporated,A TX.Corp | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2005 |
| 430 | Petrodome Operating, LLC | Houston, TX 77265 | Oil & Gas Operator | Jan 2025 |
| 431 | Petrogas Operating Corporation | Garland, TX 75043 | Oil Operator | Feb 2010 |
| 432 | Petroglyph Operating Co | Boise, ID 83709 | Oil & Gas Operator | Jul 2017 |
| 433 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 434 | Petroleum Resource Management Co | Fort Worth, TX 76107 | Oil & Gas Operator | Jan 2024 |
| 435 | Petropro Energy Partners, L.P. | Houston, TX 77024 | Oil & Gas Operator | Jan 2013 |
| 436 | PG&E Resources Company | Houston, TX 77042 | Oil & Gas Operator | May 1995 |
| 437 | PH Exploration, Inc. | Houston, TX 77008 | Oil & Gas Operator | Nov 2001 |
| 438 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 439 | Phoenix Fund, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2000 |
| 440 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 441 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | May 2025 |
| 442 | Pitchfork Oil & Gas, Inc. | Orchard, TX 77464 | Oil & Gas Operator | May 2025 |
| 443 | Placer Oil Co. | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2008 |
| 444 | Plains Exploration & Prod. Co. | Houston, TX 77002 | Oil & Gas Operator | Jul 2013 |
| 445 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 446 | Pmo | Garland, TX 75040 | Oil & Gas Operator | Feb 2018 |
| 447 | Pool Operating Corporation | Lago VIsta, TX 78645 | Oil & Gas Operator | Oct 2016 |
| 448 | Prairie Petroleum, Inc | Plano, TX 75093 | Oil & Gas Operator | May 1999 |
| 449 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 450 | Prevail Energy, Inc | Corpus Chrsti, TX 78469 | Oil & Gas Operator | May 2025 |
| 451 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | May 2025 |
| 452 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 453 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 454 | Proco Operating Co., Inc. | Graford, TX 76449 | Oil & Gas Operator | May 2025 |
| 455 | Proex Energy Management, L.L.C. | Spring, TX 77386 | Oil & Gas Operator | May 2025 |
| 456 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | May 2025 |
| 457 | Property Development Group, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | May 2025 |
| 458 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Feb 2025 |
| 459 | Quest Research & Dev. Corp. | Weatherford, TX 76086 | Oil & Gas Operator | May 2025 |
| 460 | R & B Energy, LLC | Shelby, MT 59474 | Oil Operator | Feb 2025 |
| 461 | R & S Energy Company | Luling, TX 78648 | Oil & Gas Operator | Dec 2010 |
| 462 | R & S Oil Production Co. | Luling, TX 78648 | Oil & Gas Operator | May 2025 |
| 463 | Ragars Oil & Gas Co. | Austin, TX 78716 | Oil & Gas Operator | May 2025 |
| 464 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | May 2025 |
| 465 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 466 | Ranger Oil Company | Canada, 00100 | Oil & Gas Operator | Sep 2001 |
| 467 | Reach Oil And Gas Company Inc | Oklahoma City, OK 73118-1100 | Oil & Gas Operator | Feb 2025 |
| 468 | Red Shell Inc | Dale, TX 78616 | Oil & Gas Operator | May 2025 |
| 469 | Red Wolf Oil Company, Inc. | Brenham, TX 77833 | Oil & Gas Operator | May 2025 |
| 470 | Redwood Operating, Inc. | Houston, TX 77058 | Oil & Gas Operator | May 2025 |
| 471 | Remora Management, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | May 2025 |
| 472 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 473 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | May 2025 |
| 474 | Repsol Oil & Gas USA, LLC | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 475 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | May 2025 |
| 476 | Riddle Engineering Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 477 | Riggs, Don R. | San Antonio, TX 78270 | Oil & Gas Operator | Aug 2003 |
| 478 | Riley Exploration Opg Co, LLC | La Grange, TX 78945 | Oil & Gas Operator | May 2025 |
| 479 | Riley Exploration, LLC | Blanchard, OK 73010 | Oil & Gas Operator | May 2025 |
| 480 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | May 2025 |
| 481 | Rio Bravo Expl. & Prod. Co. | Houston, TX 77055 | Oil & Gas Operator | Apr 2020 |
| 482 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 483 | Robertson Resources, Inc. | Midland, TX 79708 | Oil & Gas Operator | May 2025 |
| 484 | Rocc Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Apr 2024 |
| 485 | Rocc Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | May 2025 |
| 486 | Rocker A Operating Company | Post, TX 79356 | Oil & Gas Operator | Aug 2022 |
| 487 | Rockoil Energy Of Texas, Inc. | Weatherford, TX 76086 | Oil & Gas Operator | May 2025 |
| 488 | Rocky Creek Resources, LLC | Houston, TX 77055 | Oil & Gas Operator | May 2025 |
| 489 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 490 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | May 2025 |
| 491 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 492 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 493 | Runion Oil, Inc. | Boerne, TX 78006 | Oil & Gas Operator | Aug 2003 |
| 494 | S & C Construction, Inc. | Whitefish, MT 59937 | Oil & Gas Operator | May 2025 |
| 495 | S.B. Street Operating, Inc. | Graham, TX 76450 | Oil & Gas Operator | May 2025 |
| 496 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 497 | Sabine Oil & Gas LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 498 | Sable Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Nov 1999 |
| 499 | Salvador Oil, LLC | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 500 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |