| 501 | Pennzenergy Exp. & Prod., L.L.C. | Houston, TX 77210 | Oil & Gas Operator | Mar 2000 |
| 502 | Pennzoil Exploration & Production Co. | Carthage, TX 75633 | Oil & Gas Operator | Mar 2008 |
| 503 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Aug 2026 |
| 504 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 505 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2026 |
| 506 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 507 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Aug 2026 |
| 508 | Petropro Energy Partners, L.P. | Houston, TX 77024 | Oil & Gas Operator | Jan 2013 |
| 509 | Petrosearch Operating Co, LLC | Denver, CO 80202 | Oil & Gas Operator | Aug 2026 |
| 510 | Petrovybe Opco LLC | Plano, TX 75093 | Oil & Gas Operator | Aug 2026 |
| 511 | Pgo, Inc. | Houston, TX 77042 | Oil & Gas Operator | Jun 1999 |
| 512 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 513 | Phoenix Fund, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2000 |
| 514 | Phylko Energy Corporation | Houston, TX 77056 | Oil & Gas Operator | Aug 2003 |
| 515 | Pickens Company, Inc., The | Dallas, TX 75225 | Oil & Gas Operator | Jan 2025 |
| 516 | Pintex Operating Inc. | Corpus Chrsti, TX 78478 | Oil & Gas Operator | Feb 2005 |
| 517 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Aug 2026 |
| 518 | Pioneer Resources Producing, L.P | Irving, TX 75039 | Oil & Gas Operator | Feb 2001 |
| 519 | Pitchfork Oil & Gas, Inc. | Orchard, TX 77464 | Oil & Gas Operator | Aug 2026 |
| 520 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 521 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | May 2026 |
| 522 | Premier Minerals, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Aug 2026 |
| 523 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Aug 2026 |
| 524 | Pride Exploration, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jul 2015 |
| 525 | Prime Operating Company | Midland, TX 79705 | Oil & Gas Operator | Aug 2026 |
| 526 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 527 | Progenies Operating LLC | Austin, TX 78746 | Oil & Gas Operator | Aug 2026 |
| 528 | Proline Energy Resources Inc | Sugar Land, TX 77479 | Oil & Gas Operator | Aug 2026 |
| 529 | Property Development Group, Inc. | San Antonio, TX 78212 | Oil & Gas Operator | Aug 2026 |
| 530 | Pure Resources, L.P. | Midland, TX 79701 | Oil & Gas Operator | Mar 2006 |
| 531 | Quintana Pet. Corp. | Refugio, TX 78377 | Oil & Gas Operator | Dec 2000 |
| 532 | Quisto Energy Corp. | Kerrville, TX 78029 | Oil & Gas Operator | Jan 1998 |
| 533 | Ragars Oil & Gas Co. | Austin, TX 78746 | Oil & Gas Operator | Aug 2026 |
| 534 | Ramsower Minerals Corporation | Beeville, TX 78104 | Oil & Gas Operator | Sep 2013 |
| 535 | Ramtex Energy LLC | Tulsa, OK 74114 | Oil & Gas Operator | Aug 2026 |
| 536 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 537 | Raven Forest Operating, LLC | Hot Springs V, AR 71909 | Oil & Gas Operator | Aug 2026 |
| 538 | RCM Engineering, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Sep 2003 |
| 539 | Redwood Operating, Inc. | Houston, TX 77058 | Oil & Gas Operator | Aug 2026 |
| 540 | Regal Petroleum Services | Euless, TX 76039 | Oil & Gas Operator | Aug 2002 |
| 541 | Reh Energy, Inc. | Corpus Christ, TX 78413 | Oil & Gas Operator | Aug 2026 |
| 542 | Reliance Energy, Inc. | Austin, TX 78746 | Oil & Gas Operator | Aug 2026 |
| 543 | Remora Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Aug 2026 |
| 544 | Reneau, James Seed Co. | Shamrock, TX 79079 | Oil & Gas Operator | Aug 2026 |
| 545 | Renuergy LLC | Houston, TX 77024 | Oil & Gas Operator | Jan 2024 |
| 546 | Resaca Resources, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Aug 2026 |
| 547 | Reserve Operating Corp. | Houston, TX 77040 | Oil & Gas Operator | Aug 2026 |
| 548 | Riddle Engineering Corp. | Corpus Christ, TX 78401 | Oil & Gas Operator | Jul 2011 |
| 549 | Riley Exploration Opg Co, LLC | La Grange, TX 78945 | Oil & Gas Operator | Aug 2026 |
| 550 | Riley Exploration, LLC | Blanchard, OK 73010 | Oil & Gas Operator | Aug 2026 |
| 551 | Rincon Petroleum Corporation | Corpus Chrsti, TX 78427 | Oil & Gas Operator | Aug 2026 |
| 552 | Rio Bravo Oil Company | The Woodlands, TX 77381 | Oil & Gas Operator | Feb 2002 |
| 553 | Rio Exploration Company | San Antonio, TX 78209 | Gas Operator | Dec 2005 |
| 554 | Rio-Tex, Inc. | San Antonio, TX 78258 | Oil & Gas Operator | Aug 2026 |
| 555 | Rise Petroleum Investments LLC | Tomball, TX 77377 | Oil & Gas Operator | Aug 2026 |
| 556 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 557 | Roberson Oil Company | Houston, TX 77046 | Oil & Gas Operator | May 2026 |
| 558 | Robison, J. H. & Assoc. LTD. | Corpus Christ, TX 78413 | Oil & Gas Operator | Apr 1996 |
| 559 | Rock Resources, Inc. | Corpus Chrsti, TX 78414 | Oil & Gas Operator | Aug 2026 |
| 560 | Rodel Oil & Gas Company | Houston, TX 77218 | Oil & Gas Operator | Aug 2026 |
| 561 | Rodeo Resources, L.L.C. | Houston, TX 77079 | Oil & Gas Operator | Dec 2024 |
| 562 | Rodessa Operating Company | Corpus Chrsti, TX 78426 | Oil & Gas Operator | Aug 2026 |
| 563 | Rollert Co., Inc., The | Luling, TX 78648 | Oil & Gas Operator | Nov 2000 |
| 564 | Roma Oil And Gas, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Aug 2026 |
| 565 | Roseland Oil & Gas Inc | Rockwall, TX 75087 | Oil & Gas Operator | Feb 2003 |
| 566 | Rosewood Resources Inc | Dallas, TX 75201 | Oil & Gas Operator | Aug 2026 |
| 567 | Royal Oil & Gas Corp. | Indiana, PA 15701 | Oil & Gas Operator | Apr 2014 |
| 568 | Royal Production Company, Inc. | Corpus Christ, TX 78401 | Oil & Gas Operator | Aug 2026 |
| 569 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 570 | Sable Energy Corp. | Houston, TX 77057 | Oil & Gas Operator | Nov 1999 |
| 571 | Salvador Oil, LLC | Dallas, TX 75201 | Oil & Gas Operator | Aug 2026 |
| 572 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 573 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 574 | Samson Lone Star LP | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2007 |
| 575 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2026 |
| 576 | San Antonio Gas & Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Feb 2000 |
| 577 | Sanchez Exploration Company LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2024 |
| 578 | Sanchez Oil & Gas Corporation | Houston, TX 77056 | Oil & Gas Operator | Aug 2026 |
| 579 | Sanchez-O'Brien Oil & Gas Corp | Houston, TX 77057 | Oil & Gas Operator | May 1998 |
| 580 | Sand Springs Oil & Gas Co. | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2026 |
| 581 | Santos USA Corp. | Houston, TX 77042 | Oil & Gas Operator | Dec 2008 |
| 582 | Saxet Petroleum, Inc. | Houston, TX 77057 | Oil & Gas Operator | Aug 2026 |
| 583 | Scoggins Oil & Gas Co. | Seabrook, TX 77586 | Oil & Gas Operator | Jun 2000 |
| 584 | Scorpion Oil & Gas, LLC | Houston, TX 77036 | Oil & Gas Operator | May 2026 |
| 585 | Scully And Smith Oil Corporation | Salado, TX 76571 | Oil & Gas Operator | Feb 1995 |
| 586 | Scully Energy Corporation | Salado, TX 76571 | Oil & Gas Operator | Mar 2012 |
| 587 | Sedona Oil & Gas Corporation | Dallas, TX 75231 | Oil & Gas Operator | Aug 2026 |
| 588 | Seguro Well Service, Inc. | Gonzales, TX 78629 | Oil & Gas Operator | Aug 2026 |
| 589 | Seisgen Exploration, Inc | Houston, TX 77024 | Gas Operator | Aug 2005 |
| 590 | Senora Resources, Inc. | Dime Box, TX 77853 | Oil & Gas Operator | Aug 2026 |
| 591 | SFJV Enterprises, Inc. | Berclair, TX 78107 | Gas Operator | Aug 1998 |
| 592 | Shanghai Energy Corporation | Houston, TX 77027 | Oil & Gas Operator | Apr 2003 |
| 593 | Sheridan Energy,Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 594 | Shidler, Mark L., Inc. | Houston, TX 77055 | Oil & Gas Operator | Aug 2026 |
| 595 | Siana Oil & Gas | Conroe, TX 77305 | Oil & Gas Operator | Aug 2026 |
| 596 | Siegfried R H Inc | Tulsa, OK 74104 | Oil & Gas Operator | Mar 2008 |
| 597 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 598 | Slack Oil & Gas | Refugio, TX 78377 | Oil & Gas Operator | Dec 2012 |
| 599 | SM Operating Company LLC | Austin, TX 78709 | Oil & Gas Operator | Aug 2026 |
| 600 | Smith Operating And MGMT Co. | Shreveport, LA 71161 | Oil & Gas Operator | Jun 2023 |