| 401 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 402 | Optima Exploration LLC | Tulsa, OK 74116-5664 | Oil & Gas Operator | Mar 2015 |
| 403 | Oshtah Oil Company LLC | Stratford, OK 74872 | Oil & Gas Operator | Sep 2018 |
| 404 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 405 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Dec 2025 |
| 406 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 407 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 408 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Feb 2026 |
| 409 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 410 | Pal Kids Inc | Coronado, CA 92118 | Oil & Gas Operator | Nov 2000 |
| 411 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Feb 2026 |
| 412 | Paluca Petroleum Inc | Holdenville, OK 74848 | Oil & Gas Operator | Nov 2025 |
| 413 | Panada Exploration, Inc. | Tulsa, OK 74135 | Oil & Gas Operator | Jun 1996 |
| 414 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 415 | Pantera Energy Company | Amarillo, TX 79101 | Oil & Gas Operator | Feb 2026 |
| 416 | Park Avenue Exploration Corp | Oklahoma City, OK 73102-5604 | Oil & Gas Operator | Sep 2011 |
| 417 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 418 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 419 | Passmore Robert W | Ada, OK 74820-5501 | Oil & Gas Operator | May 2022 |
| 420 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 421 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 422 | Pedestal Oil Company Inc | Oklahoma City, OK 73101-1522 | Oil & Gas Operator | May 2019 |
| 423 | Pennant Energy LLC | Oklahoma City, OK 73116 | Oil Operator | Dec 2024 |
| 424 | Pennmark Resources Company | Edmond, OK 73013 | Oil & Gas Operator | Nov 2025 |
| 425 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 426 | Petro-Management Assoc., Inc. | Edmond, OK 73083-2346 | Oil & Gas Operator | Jun 2007 |
| 427 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 428 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 429 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 430 | Petroleum Resources Co | Wichita, KS 67206 | Oil & Gas Operator | May 2000 |
| 431 | Pheldon Oil Production Inc | Asher, OK 74826-2629 | Oil & Gas Operator | Nov 2025 |
| 432 | Pierce G R Oil Properties Inc | Oklahoma City, OK 73106 | Oil Operator | Feb 1999 |
| 433 | Pilgrim Brothers Oil | Tulsa, OK 74136 | Oil & Gas Operator | Feb 1992 |
| 434 | Pinnacle Corporation (The) | Broken Arrow, OK 74012 | Oil & Gas Operator | Nov 2014 |
| 435 | Pitco Production Company | Tulsa, OK 74170-2320 | Oil & Gas Operator | May 2013 |
| 436 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 437 | Porter John B | Ketchum, OK 74349-0207 | Oil & Gas Operator | May 2000 |
| 438 | Portfolio Oil Corporation | Oklahoma City, OK 73119 | Oil & Gas Operator | May 2013 |
| 439 | Post Oak Oil Company | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2013 |
| 440 | Prentice, Napier & Green, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | Dec 2025 |
| 441 | Preston Carter Oil Company | Davis, OK 73030 | Oil & Gas Operator | Nov 2025 |
| 442 | Pricor-TRC Corporation | Mounds, OK 74047 | Oil & Gas Operator | May 2013 |
| 443 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2026 |
| 444 | Primary Natural Resources III LLC | Tulsa, OK 74136-6351 | Oil & Gas Operator | Nov 2025 |
| 445 | Prime Energy Corp | Charleston, WV 25301-1707 | Oil & Gas Operator | Sep 2015 |
| 446 | Primexx Operating Corporation | Dallas, TX 75206 | Oil & Gas Operator | Mar 2024 |
| 447 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 448 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 449 | Proven Reserves Management, Inc. | Dallas, TX 75370 | Oil & Gas Operator | Nov 2025 |
| 450 | Pruitt L Oil Properties | Oklahoma City, OK 73162-7758 | Oil & Gas Operator | Dec 2000 |
| 451 | Psec Inc | Tulsa, OK 74102-0871 | Oil & Gas Operator | Dec 2016 |
| 452 | Quest Property Inc | Yukon, OK 73099 | Oil & Gas Operator | Jul 2025 |
| 453 | Questa Oil & Gas Co. | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2015 |
| 454 | Quintana Pet Okla Inc | Houston, TX 77002 | Oil & Gas Operator | Jun 1998 |
| 455 | R & H LLC | Ardmore, OK 73401-6329 | Oil & Gas Operator | Mar 2015 |
| 456 | R & N Associates | Grapevine, TX 76051 | Oil & Gas Operator | Feb 2025 |
| 457 | R & N Oil Company | Fairfax, OK 74637 | Oil & Gas Operator | May 2013 |
| 458 | R C Taylor Operating Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2025 |
| 459 | Ra-Jac LLC | Norman, OK 73072 | Oil & Gas Operator | Dec 2025 |
| 460 | Rainbo Service Company | Oklahoma City, OK 73129 | Oil & Gas Operator | Nov 2025 |
| 461 | Rainbow Oilwell Service Inc | Depew, OK 74028 | Oil & Gas Operator | Jul 2024 |
| 462 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 463 | Ramhead Petroleum Inc | Seminole, OK 74818-0848 | Oil & Gas Operator | Aug 2008 |
| 464 | Ramsey Engineering Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Apr 1993 |
| 465 | Ramsey Nichols Operating Company LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Dec 2025 |
| 466 | Ramsey Property Management LLC | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Nov 2025 |
| 467 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 468 | Rapp Oil & Gas | Oklahoma City, OK 73120 | Gas Operator | Jul 2020 |
| 469 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | Dec 2025 |
| 470 | Red River Royalty Production LLC | Crescent, OK 73028-0608 | Gas Operator | Apr 2021 |
| 471 | Redhen Oil Company | Oklahoma City, OK 73135 | Oil & Gas Operator | Sep 2024 |
| 472 | Reed Power Tongs Inc | Seminole, OK 74818 | Oil & Gas Operator | Sep 2025 |
| 473 | Reserve Exploration Co. | Tulsa, OK 74135 | Oil & Gas Operator | Dec 2007 |
| 474 | Revelation Gas & Oil Oklahoma LLC | Kansas City, KS 66103 | Oil & Gas Operator | Jul 2023 |
| 475 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Nov 2025 |
| 476 | Revere Corporation | Fort Smith, AR 72902-0908 | Oil & Gas Operator | Feb 2015 |
| 477 | Revolution Resources LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Jun 2023 |
| 478 | Rhoades Oil Co | Tulsa, OK 74136-5575 | Oil & Gas Operator | Aug 2013 |
| 479 | Ric Petroleum, Inc. | Wichita Falls, TX 76307 | Oil & Gas Operator | Aug 2003 |
| 480 | Rife Oil Properties Inc | Fort Worth, TX 76107 | Oil & Gas Operator | Feb 2026 |
| 481 | Rio Blanco Operating LLC | Victoria, TX 77904 | Oil & Gas Operator | Nov 2025 |
| 482 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 483 | RKK Production Company | Mustang, OK 73064 | Oil & Gas Operator | Dec 2025 |
| 484 | Roka Management Inc | Oklahoma City, OK 73139 | Oil & Gas Operator | Nov 2025 |
| 485 | Roka Resources Inc | Oklahoma City, OK 73139 | Oil & Gas Operator | Sep 2025 |
| 486 | Rosetta Resources Operating LP | San Antonio, TX 78216 | Oil & Gas Operator | Feb 2026 |
| 487 | Rough Rider Oil LLC | Booker, TX 79005-0427 | Oil & Gas Operator | Dec 2025 |
| 488 | Rox Exploration Inc | Norman, OK 73069-6301 | Oil & Gas Operator | Nov 2025 |
| 489 | Royalty Energy Development LLC | Edmond, OK 73003 | Oil & Gas Operator | Dec 2025 |
| 490 | Rupe Oil Company Inc | Wichita, KS 67278 | Oil & Gas Operator | Sep 2025 |
| 491 | S & W Engine Supply | Oklahoma City, OK 73107 | Oil Operator | Jun 2003 |
| 492 | S & W Engine Supply Inc | Oklahoma City, OK 73143 | Oil Operator | Jan 2000 |
| 493 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 494 | Sabre Operating, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 495 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 496 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2025 |
| 497 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Feb 2026 |
| 498 | Sandrock Energy LLC | Luther, OK 73054 | Oil & Gas Operator | Nov 2025 |
| 499 | Sanner Oil Company | Velma, OK 73491-0550 | Oil & Gas Operator | Jan 2014 |
| 500 | Sanook Inc | Oklahoma City, OK 73156-0548 | Oil & Gas Operator | Jan 2007 |