| 501 | Northwest Oil Company | Dallas, TX 75204 | Oil & Gas Operator | Jun 2014 |
| 502 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 503 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Feb 2025 |
| 504 | Obele Operating Company LLC | Sedona, AZ 86336-5745 | Oil & Gas Operator | Jan 2025 |
| 505 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 506 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Apr 2025 |
| 507 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Jan 2025 |
| 508 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 509 | Oklahoma & Northwestern Co. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jan 1997 |
| 510 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 511 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jan 2025 |
| 512 | Oklahoma Petroleum Allies LLC | Ardmore, OK 73401 | Oil Operator | Oct 2023 |
| 513 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 514 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Feb 2025 |
| 515 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 516 | Oneok Gas Processing LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 517 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 518 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 519 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 520 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Feb 2025 |
| 521 | Oryx Crude Trading & Transporation LP | Dallas, TX 75221 | Oil & Gas Operator | Jun 1999 |
| 522 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Feb 2025 |
| 523 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Feb 2025 |
| 524 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Apr 2025 |
| 525 | Oxley Petroleum | Tulsa, OK 74119-3609 | Oil & Gas Operator | Jan 2020 |
| 526 | Oxley Petroleum Co | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 527 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2025 |
| 528 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 529 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Apr 2025 |
| 530 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 531 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 532 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 533 | Para Pro Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | Jan 2005 |
| 534 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 535 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 536 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 537 | Parks Jack Concrete Co | Hominy, OK 74035 | Oil Operator | Jan 2025 |
| 538 | Parks James L | Edmond, OK 73034 | Oil & Gas Operator | Aug 2005 |
| 539 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 540 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 541 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Jan 2025 |
| 542 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 543 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |
| 544 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 545 | Pelican Production Company | New Orleans, LA 70130-2477 | Oil & Gas Operator | Mar 2014 |
| 546 | Pengo Petroleum, Inc. | | Oil & Gas Operator | Dec 2013 |
| 547 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Jan 2025 |
| 548 | Penner Energy Inc | Oklahoma City, OK 73120-1930 | Oil & Gas Operator | Feb 2025 |
| 549 | Pennmark Resources Company | Edmond, OK 73013 | Oil & Gas Operator | Jan 2025 |
| 550 | Perkins Energy Company | Duncan, OK 73533-3853 | Oil & Gas Operator | Feb 2025 |
| 551 | Perkins Production Company Inc | Seminole, OK 74868 | Oil & Gas Operator | May 2006 |
| 552 | Pet-Ex, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2024 |
| 553 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 554 | Petro-Haley | Borger, TX 79008 | Oil & Gas Operator | Apr 2025 |
| 555 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 556 | Petroco Inc | | Oil & Gas Operator | Nov 1996 |
| 557 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 558 | Petroleum Exploration Company LTD LP | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2025 |
| 559 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 560 | Petroleum Production MGMT., Inc. | Kansas City, MO 64112 | Oil & Gas Operator | Apr 2025 |
| 561 | Phoenix Oil & Gas Inc | Seminole, OK 74868 | Oil & Gas Operator | Jan 2025 |
| 562 | Phoenix Petrocorp, Inc. | McKinney, TX 75070 | Oil & Gas Operator | Feb 2025 |
| 563 | Phoenix Production Inc | Burneyville, OK 73430-2158 | Oil & Gas Operator | Jan 2025 |
| 564 | Pioneer Natural Res. USA, Inc. | Irving, TX 75038 | Oil & Gas Operator | Apr 2025 |
| 565 | Pixley Carlis D | Marlow, OK 73055 | Oil & Gas Operator | Sep 1999 |
| 566 | Plains Liquids Transport Inc | Houston, TX 77002 | Oil & Gas Operator | May 1996 |
| 567 | Plains Marketing & Trans Inc | Houston, TX 76002 | Oil & Gas Operator | Oct 1998 |
| 568 | Plains Marketing LP | Cushing, OK 74023 | Oil & Gas Operator | Dec 2022 |
| 569 | Polaris Energy Dev Co | Tulsa, OK 74135 | Oil & Gas Operator | Apr 2000 |
| 570 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 571 | Presidio Petroleum LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |
| 572 | Pri Producing Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2006 |
| 573 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2025 |
| 574 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 575 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 576 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 577 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 578 | Pruitt Operating Company LLC | Ratliff City, OK 73481-5802 | Oil & Gas Operator | Feb 2025 |
| 579 | Psec Inc | Tulsa, OK 74102-0871 | Oil & Gas Operator | Dec 2016 |
| 580 | Pyramid Energy Inc | San Antonio, TX 78216 | Oil & Gas Operator | Feb 2012 |
| 581 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Jan 2025 |
| 582 | Quail Creek Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Apr 2025 |
| 583 | Quail Creek Petro MGMT Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Aug 2013 |
| 584 | Questa Oil & Gas Co. | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2015 |
| 585 | Questar Energy Trading | Salt Lake City, UT 84145-0601 | Oil & Gas Operator | Mar 2020 |
| 586 | Questar Explor & Prod Co | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2017 |
| 587 | R & C Oil And Gas Inc | Ada, OK 74820-3150 | Oil Operator | Jul 2016 |
| 588 | R & H LLC | Ardmore, OK 73401-6329 | Oil & Gas Operator | Mar 2015 |
| 589 | R L Clampitt & Associates LLC | Bartlesville, OK 74006 | Oil & Gas Operator | Feb 2025 |
| 590 | Ra-Jac LLC | Norman, OK 73072 | Oil & Gas Operator | Feb 2025 |
| 591 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 592 | Ramsey Nichols Operating Company LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Feb 2025 |
| 593 | Ramsey Property Management LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Dec 2024 |
| 594 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 595 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 596 | Range Production Company, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2025 |
| 597 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Jan 2025 |
| 598 | Raw Crude Oil & Gas LLC | Norman, OK 73069 | Oil & Gas Operator | Feb 2025 |
| 599 | Raw Production LLC | Lindsay, OK 73052 | Oil & Gas Operator | Feb 2025 |
| 600 | Raydon Exploration, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Apr 2025 |