| 401 | Opal Energy, Inc. | Katy, TX 77494 | Oil & Gas Operator | Jun 2009 |
| 402 | Osyka Producing Company, Inc. | Houston, TX 77242 | Oil & Gas Operator | Apr 2025 |
| 403 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | Apr 2025 |
| 404 | Overflow Energy, LLC | Booker, TX 79005 | Oil & Gas Operator | Apr 2025 |
| 405 | Overton Park Oil & Gas LP | Fort Worth, TX 76109 | Oil & Gas Operator | Apr 2025 |
| 406 | Ozark Exploration, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Apr 2025 |
| 407 | Pa Prospect LLC | Columbus, MT 59019 | Oil & Gas Operator | Jul 2020 |
| 408 | Padon, Frank B. Oil Oper., Inc. | Houston, TX 77227 | Oil & Gas Operator | Nov 1998 |
| 409 | Paradis Investments, L.L.C. | Bellaire, TX 77401 | Oil Operator | Jun 2020 |
| 410 | Parker & Parsley Development Co. | Midland, TX 79702 | Oil & Gas Operator | May 1995 |
| 411 | Parker & Parsley Development L.P | Midland, TX 79702 | Oil & Gas Operator | Oct 2007 |
| 412 | Parker & Parsley Producing LP | Midland, TX 79702 | Oil & Gas Operator | Oct 1997 |
| 413 | Partners Oil Company | Tulsa, OK 74135 | Oil & Gas Operator | Aug 1995 |
| 414 | Patara Oil & Gas LLC | Dallas, TX 75219 | Oil & Gas Operator | Mar 2018 |
| 415 | Patterson Petroleum LLC | Snyder, TX 79550 | Oil & Gas Operator | Oct 2007 |
| 416 | Patterson Petroleum LP | Snyder, TX 79550 | Oil & Gas Operator | Mar 2008 |
| 417 | Peach Creek Operating Co, LLC | Houston, TX 77007 | Oil & Gas Operator | Apr 2025 |
| 418 | Pecos Petroleum Company | Houston, TX 77057 | Oil & Gas Operator | Oct 1999 |
| 419 | Pegasus Operating, Inc. | Coldspring, TX 77331 | Oil & Gas Operator | Apr 2025 |
| 420 | Penn VIrginia Oil & Gas Corp | Houston, TX 77024 | Oil & Gas Operator | Dec 2023 |
| 421 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 422 | Peoples Energy Prod.-TX, L.P. | Houston, TX 77002 | Oil & Gas Operator | Sep 2007 |
| 423 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 424 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 425 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 426 | Petrocorp Acquisition Company | Tulsa, OK 74121 | Oil & Gas Operator | Dec 2002 |
| 427 | Petrocorp Incorporated,A TX.Corp | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2005 |
| 428 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 429 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 430 | Petrolero Corp. | San Antonio, TX 78205 | Oil & Gas Operator | Feb 1998 |
| 431 | Petroleum Advisors Int'L., Inc. | Houston, TX 77224 | Gas Operator | Jun 2005 |
| 432 | Petropro Energy Partners, L.P. | Houston, TX 77024 | Oil & Gas Operator | Jan 2013 |
| 433 | Petrosearch Operating Co, LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 434 | PG&E Resources Company | Houston, TX 77042 | Oil & Gas Operator | May 1995 |
| 435 | Pie Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2025 |
| 436 | Pintail Production Co., Inc. | Fort Worth, TX 76132 | Oil & Gas Operator | Apr 2025 |
| 437 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | Apr 2025 |
| 438 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 439 | Plains Production Inc | Wichita Falls, TX 76308 | Oil & Gas Operator | Dec 1995 |
| 440 | Pmo | Garland, TX 75040 | Oil & Gas Operator | Feb 2018 |
| 441 | Poco LLC | Houston, TX 77270 | Oil & Gas Operator | Apr 2025 |
| 442 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 443 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Apr 2025 |
| 444 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Apr 2025 |
| 445 | Premium Exploration Company | Early, TX 76803 | Oil & Gas Operator | Apr 2025 |
| 446 | Presidio Exploration, Inc. | Englewood, CO 80155 | Oil & Gas Operator | May 1999 |
| 447 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 448 | Producers Energy Corporation | Houston, TX 77002 | Oil & Gas Operator | Aug 2000 |
| 449 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Apr 2025 |
| 450 | Property Development Group, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Apr 2025 |
| 451 | Property Producing Co. | Columbus, TX 78934 | Gas Operator | Apr 2025 |
| 452 | Puls, W. L. | Houston, TX 77084 | Oil & Gas Operator | Sep 2002 |
| 453 | Pure Resources, L.P. | Midland, TX 79701 | Oil & Gas Operator | Mar 2006 |
| 454 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 455 | R & S Energy Company | Luling, TX 78648 | Oil & Gas Operator | Dec 2010 |
| 456 | Ragars Oil & Gas Co. | Austin, TX 78716 | Oil & Gas Operator | Apr 2025 |
| 457 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | Apr 2025 |
| 458 | Rana Energy Company | Spring, TX 77387 | Oil & Gas Operator | Mar 2008 |
| 459 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 460 | Rawhide Operating, Inc. | New Braunfels, TX 78131 | Oil & Gas Operator | Apr 2025 |
| 461 | Ray Loveless Enterprises, L.L.C. | Kilgore, TX 75663 | Oil Operator | Apr 2025 |
| 462 | Red Fork Production, LLC | San Antonio, TX 78217 | Oil & Gas Operator | Jan 2025 |
| 463 | Redwood Operating, Inc. | Houston, TX 77058 | Oil & Gas Operator | Apr 2025 |
| 464 | Reef Exploration, Inc. (A-1) | Richardson, TX 75080 | Oil & Gas Operator | Oct 2006 |
| 465 | Reef Exploration, L.P. | Richardson, TX 75080 | Oil & Gas Operator | Apr 2025 |
| 466 | Remora Management, LLC | The Woodlands, TX 77382 | Oil & Gas Operator | Apr 2025 |
| 467 | Reo Operating LLC | Austin, TX 78747 | Oil & Gas Operator | Apr 2025 |
| 468 | Republic Resources, LLC. | San Antonio, TX 78212 | Oil & Gas Operator | Apr 2025 |
| 469 | Resaca Resources, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Apr 2025 |
| 470 | Rfe Operating, LLC | Tyler, TX 75703 | Oil & Gas Operator | Apr 2025 |
| 471 | Richardson Operating Company | Denver, CO 80237 | Oil & Gas Operator | Feb 2025 |
| 472 | Richardson, Marshall T. | Midfield, TX 77458 | Oil & Gas Operator | Apr 2025 |
| 473 | Riddle Engineering Corp. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 474 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Apr 2025 |
| 475 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 476 | Rise Petroleum Investments LLC | Tomball, TX 77377 | Oil & Gas Operator | Apr 2025 |
| 477 | Rocc Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Apr 2024 |
| 478 | Rocc Operating, LLC | Houston, TX 77084 | Oil & Gas Operator | Apr 2025 |
| 479 | Rockoil Energy Of Texas, Inc. | Weatherford, TX 76086 | Oil & Gas Operator | Apr 2025 |
| 480 | Rocky Creek Resources, LLC | Houston, TX 77055 | Oil & Gas Operator | Apr 2025 |
| 481 | Rosewood Resources, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2025 |
| 482 | Rotation, Incorporated | Houston, TX 77057 | Oil & Gas Operator | Mar 2023 |
| 483 | Royal Production Company, Inc. | Corpus Chrsti, TX 78401 | Oil & Gas Operator | Apr 2025 |
| 484 | Rudman Partnership, The | Dallas, TX 75201 | Oil & Gas Operator | Dec 2014 |
| 485 | Rutta, Jim | Columbus, TX 78934 | Oil & Gas Operator | Dec 1995 |
| 486 | Sabco Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2011 |
| 487 | Sabco Operating Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Jun 2018 |
| 488 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 489 | Sabine Oil & Gas LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 490 | Salt Creek Production, Inc. | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2025 |
| 491 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 492 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2025 |
| 493 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Apr 2025 |
| 494 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 495 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Apr 2025 |
| 496 | Santos USA Corp. | Houston, TX 77042 | Oil & Gas Operator | Dec 2008 |
| 497 | Saxet Energy, LTD. | Houston, TX 77057 | Oil & Gas Operator | Mar 2004 |
| 498 | Scully Energy Corporation | Salado, TX 76571 | Oil & Gas Operator | Mar 2012 |
| 499 | Sedona Oil & Gas Corporation | Austin, TX 78746 | Oil & Gas Operator | Apr 2025 |
| 500 | Seely Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |