| 501 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 502 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 503 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Mar 2026 |
| 504 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Mar 2026 |
| 505 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Mar 2026 |
| 506 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Jun 2026 |
| 507 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 508 | Oxley Petroleum Company | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 509 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jun 2026 |
| 510 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 511 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Jun 2026 |
| 512 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 513 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 514 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 515 | Para Pro Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | Jan 2005 |
| 516 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 517 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 518 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 519 | Parks Jack Concrete Co | Hominy, OK 74035 | Oil Operator | Aug 2025 |
| 520 | Parks James L | Edmond, OK 73034 | Oil & Gas Operator | Aug 2005 |
| 521 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 522 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 523 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Feb 2026 |
| 524 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 525 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |
| 526 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 527 | Pelican Production Company | New Orleans, LA 70130-2477 | Oil & Gas Operator | Mar 2014 |
| 528 | Pengo Petroleum Inc | | Oil & Gas Operator | Dec 2013 |
| 529 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Sep 2025 |
| 530 | Penner Energy Inc | Oklahoma City, OK 73120-1930 | Oil & Gas Operator | Mar 2026 |
| 531 | Pennmark Resources Company | Edmond, OK 73013 | Oil & Gas Operator | Mar 2026 |
| 532 | Perkins Energy Company | Duncan, OK 73533-3853 | Oil & Gas Operator | Mar 2026 |
| 533 | Pet-Ex Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 2026 |
| 534 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 535 | Petro-Haley | Borger, TX 79008 | Oil & Gas Operator | Jun 2026 |
| 536 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 537 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 538 | Petroleum Exploration Company LTD LP | Breckenridge, TX 76424 | Oil & Gas Operator | Mar 2026 |
| 539 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 540 | Petroleum Production MGMT., Inc. | Kansas City, MO 64112 | Oil & Gas Operator | Jun 2026 |
| 541 | Phoenix Oil & Gas Inc | Seminole, OK 74868 | Oil & Gas Operator | May 2025 |
| 542 | Phoenix Petrocorp, Inc. | McKinney, TX 75070 | Oil & Gas Operator | Mar 2026 |
| 543 | Phoenix Production Inc | Burneyville, OK 73430-2158 | Oil & Gas Operator | Feb 2025 |
| 544 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Jun 2026 |
| 545 | Pixley Carlis D | Marlow, OK 73055 | Oil & Gas Operator | Sep 1999 |
| 546 | Polaris Energy Dev Co | Tulsa, OK 74135 | Oil & Gas Operator | Apr 2000 |
| 547 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 548 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Jun 2026 |
| 549 | Pri Producing Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 550 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Jun 2026 |
| 551 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 552 | Prime Operating Company | Midland, TX 79705 | Oil & Gas Operator | Jun 2026 |
| 553 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 554 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 555 | Pruitt Operating Company LLC | Ratliff City, OK 73481-5802 | Oil & Gas Operator | Mar 2026 |
| 556 | Psec Inc | Tulsa, OK 74102-0871 | Oil & Gas Operator | Dec 2016 |
| 557 | Pyramid Energy Inc | San Antonio, TX 78216 | Oil & Gas Operator | Feb 2012 |
| 558 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 559 | Quail Creek Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Jun 2026 |
| 560 | Quail Creek Petro MGMT Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Aug 2013 |
| 561 | Questa Oil & Gas Co. | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2015 |
| 562 | Questar Explor & Prod Co | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2017 |
| 563 | R & C Oil And Gas Inc | Ada, OK 74820-3150 | Oil Operator | Jul 2016 |
| 564 | R & H LLC | Ardmore, OK 73401-6329 | Oil & Gas Operator | Mar 2015 |
| 565 | R L Clampitt & Associates LLC | Bartlesville, OK 74006 | Oil & Gas Operator | Mar 2026 |
| 566 | Ra-Jac LLC | Norman, OK 73069 | Oil & Gas Operator | Mar 2026 |
| 567 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 568 | Ramsey Nichols Operating Company LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Feb 2026 |
| 569 | Ramsey Property Management LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Jan 2026 |
| 570 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 571 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 572 | Range Production Company, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2026 |
| 573 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Feb 2026 |
| 574 | Raw Crude Oil & Gas, L.L.C. | Norman, OK 73069 | Oil & Gas Operator | Feb 2026 |
| 575 | Raw Production LLC | Lindsay, OK 73052 | Oil & Gas Operator | Mar 2026 |
| 576 | Raydon Exploration, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Jun 2026 |
| 577 | RB Operating Company | Shawnee, OK 74802-1488 | Oil & Gas Operator | Apr 2015 |
| 578 | RDH Enterprises Inc | El Reno, OK 73036 | Oil & Gas Operator | May 2015 |
| 579 | Reading & Bates Petroleum Co | Tulsa, OK 74136 | Oil & Gas Operator | Aug 2009 |
| 580 | Rebellion Energy LLC | Tulsa, OK 74135-6241 | Oil & Gas Operator | Jun 2022 |
| 581 | Red Bluff Resources Operating LLC | Oklahoma City, OK 73112-5468 | Oil & Gas Operator | Feb 2026 |
| 582 | Red Earth Oil & Gas, Inc. | Oklahoma City, OK 73159 | Oil & Gas Operator | Oct 2021 |
| 583 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | Mar 2026 |
| 584 | Red Rocks Oil & Gas Operating LLC | Oklahoma City, OK 73103 | Oil & Gas Operator | Mar 2026 |
| 585 | Red Wolf Operating LLC | Edmond, OK 73003-2179 | Oil & Gas Operator | Mar 2026 |
| 586 | Redland Resources LLC | Oklahoma City, OK 73127 | Oil & Gas Operator | Mar 2026 |
| 587 | Redline Energy LLC | Dover, OK 73734 | Oil & Gas Operator | Mar 2026 |
| 588 | Regency Exploration Inc | Oklahoma City, OK 73102-5605 | Oil & Gas Operator | Mar 1999 |
| 589 | Research Oil Company Inc | Norman, OK 73070-8776 | Oil & Gas Operator | Aug 2019 |
| 590 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Feb 2026 |
| 591 | Revilo Exploration, Inc. | Richardson, TX 75081 | Oil & Gas Operator | Jul 2021 |
| 592 | Revolution Operating Company,LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Jul 2024 |
| 593 | Ricks Exploration Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 594 | Rimrock Resource Operating LLC | Tulsa, OK 74103-4462 | Oil & Gas Operator | Mar 2026 |
| 595 | Rio Grande Drilling Company | San Antonio, TX 78212 | Oil & Gas Operator | Dec 1999 |
| 596 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2026 |
| 597 | Rja Energy LLC | Norman, OK 73069-8224 | Oil & Gas Operator | Mar 2026 |
| 598 | RKK Production Company | Mustang, OK 73064 | Oil & Gas Operator | Mar 2026 |
| 599 | Roan Resources LLC | Tulsa, OK 74103-3729 | Oil & Gas Operator | Apr 2024 |
| 600 | Roberson Oil Company | Houston, TX 77046 | Oil & Gas Operator | Mar 2026 |