| 401 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 402 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Jan 2026 |
| 403 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 404 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Feb 2026 |
| 405 | Olympic Petroleum Co | Tulsa, OK 74114 | Oil & Gas Operator | Jun 1998 |
| 406 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 407 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 408 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 409 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Apr 2026 |
| 410 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Feb 2026 |
| 411 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 412 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Feb 2026 |
| 413 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Apr 2026 |
| 414 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Apr 2026 |
| 415 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 416 | Panadero Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Apr 2002 |
| 417 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 418 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 419 | Panhandle Oil & Gas Consultants Inc | Woodward, OK 73802-5011 | Oil & Gas Operator | Jul 2015 |
| 420 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Apr 2026 |
| 421 | Paramore Oil Company | Duncan, OK 73533 | Oil & Gas Operator | Apr 2022 |
| 422 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 423 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 424 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 425 | Parwest Land Exploration Inc | Oklahoma City, OK 73112 | Oil & Gas Operator | Jan 2026 |
| 426 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 427 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Jan 2026 |
| 428 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 429 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |
| 430 | Petra Petroleum Inc | Littleton, CO 80160-0319 | Oil & Gas Operator | Jun 2005 |
| 431 | Petro Energy Inc | Farmington, NM 87499 | Oil & Gas Operator | Sep 2025 |
| 432 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 433 | Petroleum Corporation Of Texas | Breckenridge, TX 76024 | Oil & Gas Operator | May 2002 |
| 434 | Petroleum Resources Co | Wichita, KS 67206 | Oil & Gas Operator | May 2000 |
| 435 | Petroquest Energy, L.L.C. | Lafayette, LA 70505 | Oil & Gas Operator | Apr 2026 |
| 436 | Pharoah Bob | Maysville, OK 73057 | Oil & Gas Operator | Jul 1994 |
| 437 | Pices Energy Production Co. | Alva, OK 73717-9512 | Oil & Gas Operator | Apr 2014 |
| 438 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 439 | Plenergy Dev LTD | | Oil & Gas Operator | Jun 2004 |
| 440 | Pollok Energy LLC | Tulsa, OK 74159 | Oil & Gas Operator | Feb 2026 |
| 441 | Post Petroleum Company | Oklahoma City, OK 73116 | Oil & Gas Operator | Aug 2013 |
| 442 | Premier Resources LTD | Denver, CO 80237 | Oil & Gas Operator | Jul 2002 |
| 443 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Feb 2026 |
| 444 | Presley Petroleum Company | Newport Beach, CA 92658-2200 | Oil & Gas Operator | Oct 1999 |
| 445 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Apr 2026 |
| 446 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 447 | Prime Operating Company | Midland, TX 79705 | Oil & Gas Operator | Apr 2026 |
| 448 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 449 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 450 | Providence Oil & Gas Corp | Tulsa, OK 74135-5463 | Oil & Gas Operator | May 2005 |
| 451 | Pyramid Oil Of America, Inc. | Nichols Hill, OK 73116 | Oil & Gas Operator | Jan 2026 |
| 452 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Jan 2026 |
| 453 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Jan 2026 |
| 454 | R C Taylor Operating Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Feb 2026 |
| 455 | R E Blaik Inc | Edmond, OK 73013-6675 | Oil & Gas Operator | Feb 2026 |
| 456 | Radford Dale | Konawa, OK 74849 | Oil & Gas Operator | Jan 2026 |
| 457 | Ram Asset Management Co | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 458 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 459 | Ramsey Property Management LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Jan 2026 |
| 460 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 461 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 462 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Feb 2026 |
| 463 | Raydon Exploration, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Apr 2026 |
| 464 | RB Operating Company | Shawnee, OK 74802-1488 | Oil & Gas Operator | Apr 2015 |
| 465 | RDH Enterprises Inc | El Reno, OK 73036 | Oil & Gas Operator | May 2015 |
| 466 | Red Bluff Resources Operating LLC | Oklahoma City, OK 73112-5468 | Oil & Gas Operator | Jan 2026 |
| 467 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | Feb 2026 |
| 468 | Red Rocks Oil & Gas Operating LLC | Oklahoma City, OK 73103-4821 | Oil & Gas Operator | Feb 2026 |
| 469 | Red Wolf Operating LLC | Edmond, OK 73003-2179 | Oil & Gas Operator | Feb 2026 |
| 470 | Redgate Petroleum Inc | Waynoka, OK 73860-9408 | Oil & Gas Operator | Mar 2014 |
| 471 | Redland Resources LLC | Oklahoma City, OK 73127 | Oil & Gas Operator | Feb 2026 |
| 472 | Redline Energy LLC | Dover, OK 73734 | Oil & Gas Operator | Feb 2026 |
| 473 | Redstone Oil & Gas Company | Dallas, TX 75225 | Oil & Gas Operator | Jan 2020 |
| 474 | Resource Oil And Gas, LLC | Oklahoma City, OK 73114 | Oil & Gas Operator | Apr 2026 |
| 475 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Jan 2026 |
| 476 | Richard W Thompson Inc | Plano, TX 75075 | Oil & Gas Operator | Jul 2019 |
| 477 | Ricks Exploration Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 478 | Rife Oil Properties Inc | Fort Worth, TX 76107 | Oil & Gas Operator | Apr 2026 |
| 479 | Rives Owen H | Holdenville, OK 74848-0913 | Oil & Gas Operator | Nov 2000 |
| 480 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 481 | RKK Production Company | Mustang, OK 73064 | Oil & Gas Operator | Feb 2026 |
| 482 | RMS Monte Christo, LLC | Snowmass VLG., CO 81615 | Oil & Gas Operator | Mar 2023 |
| 483 | Roberson Oil Company | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 484 | Roberts & Murphy, Inc. | Shreveport, LA 71137 | Oil & Gas Operator | Apr 2016 |
| 485 | Roberts Zetau J Fisk | Moore, OK 73160 | Oil & Gas Operator | Sep 1993 |
| 486 | Ross Curtis | Ada, OK 74820-1354 | Oil & Gas Operator | Feb 2012 |
| 487 | RTC Resources, LLP | Weatherford, OK 73096 | Oil & Gas Operator | Apr 2026 |
| 488 | Rupe Oil Company Inc | Wichita, KS 67278 | Oil & Gas Operator | Dec 2025 |
| 489 | Russell D Meloy Oil & Gas Co | Enid, OK 73703-1623 | Oil & Gas Operator | Feb 2026 |
| 490 | S & G Operating LLC | McLoud, OK 74851 | Oil & Gas Operator | Feb 2026 |
| 491 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 492 | Samson Gas Producing Company | Tulsa, OK 74103 | Oil & Gas Operator | May 2001 |
| 493 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 494 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2026 |
| 495 | Sandridge Energy, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2018 |
| 496 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Apr 2026 |
| 497 | Sanook Inc | Oklahoma City, OK 73156-0548 | Oil & Gas Operator | Jan 2007 |
| 498 | Santo Resources Inc | Oklahoma City, OK 73154 | Oil & Gas Operator | Nov 1998 |
| 499 | Scoggins Production LLC | Enid, OK 73703-3002 | Oil & Gas Operator | Feb 2026 |
| 500 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |