| 401 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2025 |
| 402 | MW Petroleum Corporation | Houston, TX 77056 | Oil & Gas Operator | Mar 2015 |
| 403 | Nadel And Gussman, L.L.C. | Tulsa, OK 74119 | Oil & Gas Operator | Jul 2025 |
| 404 | National Cooperative RFG Assoc | McPherson, KS 67460-1404 | Oil & Gas Operator | Jun 2006 |
| 405 | National Energy Group, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Sep 2014 |
| 406 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 407 | Natural Gas Pipeline Co Of Am LLC | Downers Grove, IL 60515-3708 | Oil & Gas Operator | Mar 2015 |
| 408 | Nbi Services, Inc. | Tulsa, OK 74159 | Oil & Gas Operator | Jul 2025 |
| 409 | Neg Operating LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | Nov 2024 |
| 410 | Nexus Resources Corporation | Drumright, OK 74030 | Oil & Gas Operator | Jan 2013 |
| 411 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 412 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Jul 2025 |
| 413 | Nordstrand Engineering Inc | Houston, TX 77019 | Oil & Gas Operator | Jul 2025 |
| 414 | North Lake Resources LLC | Oklahoma City, OK 73132 | Oil & Gas Operator | Jul 2025 |
| 415 | Northwest Exploration Co | Salt Lake City, UT 84108-0900 | Oil & Gas Operator | Sep 1991 |
| 416 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 417 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Apr 2025 |
| 418 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 419 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Jul 2025 |
| 420 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Apr 2025 |
| 421 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 422 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 423 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | May 2025 |
| 424 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 425 | Olympia Oil Inc | Edmond, OK 73083-7088 | Oil & Gas Operator | Jul 2020 |
| 426 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 427 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 428 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 429 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | May 2025 |
| 430 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Jul 2025 |
| 431 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | May 2025 |
| 432 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 433 | Ouachita Exploration Inc | Chickasha, OK 73018 | Oil & Gas Operator | May 2025 |
| 434 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | May 2025 |
| 435 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 436 | P & M Drilling Company Inc | Depew, OK 74028 | Oil & Gas Operator | Dec 2004 |
| 437 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Jul 2025 |
| 438 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 439 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2025 |
| 440 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 441 | Pardee Production Co. | Skiatook, OK 74070 | Oil & Gas Operator | Mar 2021 |
| 442 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 443 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 444 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 445 | Patina Oklahoma Corp | Duncan, OK 73533-9523 | Oil & Gas Operator | Nov 2014 |
| 446 | Patrick Petroleum Co. | Jackson, MI 49201 | Oil & Gas Operator | Nov 1993 |
| 447 | Patterson Bobby Ray | Haskell, OK 74436-8809 | Oil & Gas Operator | Apr 2020 |
| 448 | Payne Exploration Company | Crescent, OK 73028 | Oil & Gas Operator | Apr 2025 |
| 449 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 450 | Pengo Petroleum, Inc. | | Oil & Gas Operator | Dec 2013 |
| 451 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Jan 2025 |
| 452 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 453 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 454 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 455 | Petroleum Management, Inc. | Corpus Chrsti, TX 78471 | Oil & Gas Operator | Jul 2025 |
| 456 | Petrosearch Operating Co, LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 457 | Phoenix Petrocorp, Inc. | McKinney, TX 75070 | Oil & Gas Operator | May 2025 |
| 458 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 459 | Pioneer Resources Prod LP | Irving, TX 75039-3745 | Oil & Gas Operator | Feb 2005 |
| 460 | Piper Operating LLC | Stigler, OK 74462 | Oil & Gas Operator | Apr 2025 |
| 461 | Plains Resources Inc. | Houston, TX 77002 | Oil & Gas Operator | Jul 2008 |
| 462 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Jul 2025 |
| 463 | Prentice Napier & Green Inc | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2025 |
| 464 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Jul 2025 |
| 465 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Jul 2025 |
| 466 | Primary Natural Resources Inc. | Tulsa, OK 74136-6351 | Oil & Gas Operator | Mar 2023 |
| 467 | Prime Energy Corp | Charleston, WV 25301-1707 | Oil & Gas Operator | Sep 2015 |
| 468 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | Jul 2025 |
| 469 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 470 | Pringle Operating Co. | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2015 |
| 471 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 472 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 473 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 474 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Apr 2025 |
| 475 | Questa Energy Corporation | Amarillo, TX 79159 | Oil & Gas Operator | Jul 2025 |
| 476 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 477 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 478 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 479 | Range Production Company, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2025 |
| 480 | Rasmussen, Hal J. Operating, Inc | Midland, TX 79701 | Oil & Gas Operator | Apr 2009 |
| 481 | Ratliff City Trucking Inc | Ratliff City, OK 73481-9603 | Oil & Gas Operator | Feb 2018 |
| 482 | Raw Crude Oil & Gas LLC | Norman, OK 73069 | Oil & Gas Operator | May 2025 |
| 483 | Raydon Exploration, Inc. | Oklahoma City, OK 73118 | Oil & Gas Operator | Jul 2025 |
| 484 | RDH Enterprises, Inc. | El Reno, OK 73036 | Oil & Gas Operator | May 2015 |
| 485 | Rebellion Energy LLC | Tulsa, OK 74135-6241 | Oil & Gas Operator | Jun 2022 |
| 486 | Red Eagle Oil Company | Oklahoma City, OK 73154 | Oil & Gas Operator | Mar 2005 |
| 487 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | May 2025 |
| 488 | Red Mountain Operating LLC | Oklahoma City, OK 73118-1253 | Oil & Gas Operator | Apr 2024 |
| 489 | Red Rock Operating, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2015 |
| 490 | Red Rock Resources, L.L.C. | Wichita Falls, TX 76310 | Oil & Gas Operator | Apr 2025 |
| 491 | Red Wolf Operating LLC | Edmond, OK 73003-2179 | Oil & Gas Operator | May 2025 |
| 492 | Redgate Petroleum Inc | Waynoka, OK 73860-9408 | Oil & Gas Operator | Mar 2014 |
| 493 | Redland Resources, LLC | Oklahoma City, OK 73127 | Oil & Gas Operator | May 2025 |
| 494 | Redline Energy LLC | Dover, OK 73734 | Oil & Gas Operator | May 2025 |
| 495 | Reeder Energy Operating LLC | Dallas, TX 75206-4085 | Oil & Gas Operator | Dec 2021 |
| 496 | Renaissance Petroleum Co LLC | Houston, TX 77058 | Oil & Gas Operator | Nov 2011 |
| 497 | Resolute Wyoming Inc | Denver, CO 80203 | Oil & Gas Operator | May 2018 |
| 498 | Resource Oil And Gas, LLC | Oklahoma City, OK 73114 | Oil & Gas Operator | Jul 2025 |
| 499 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Apr 2025 |
| 500 | Richard W Thompson Inc | Plano, TX 75075 | Oil & Gas Operator | Jul 2019 |