| 401 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | Jul 2026 |
| 402 | Petro-Lewis Corp. | | Oil & Gas Operator | Feb 1994 |
| 403 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 404 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2026 |
| 405 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 406 | Petrox Resources Inc | Meeker, CO 81641 | Oil & Gas Operator | Jun 2026 |
| 407 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 408 | Phoenix Resources Co | | Oil & Gas Operator | Jun 1984 |
| 409 | Pine Haven Resources LLC | Boulder, CO 80305 | Oil Operator | Jun 2026 |
| 410 | Pioneer Exploration, LLC | Houston, TX 77090 | Oil & Gas Operator | Jun 2026 |
| 411 | Pioneer Natural Resources USA Inc | Irving, TX 75039 | Oil & Gas Operator | Mar 2026 |
| 412 | Plains Petroleum Operating Co | Denver, CO 80202 | Oil & Gas Operator | Dec 2014 |
| 413 | PML Operating LLC | | Oil Operator | May 2026 |
| 414 | Poc-I LLC | Casper, WY 82605 | Oil & Gas Operator | Jun 2026 |
| 415 | Polfam Exploration Co | Denver, CO 80204 | Oil & Gas Operator | Mar 2007 |
| 416 | Polumbus Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 1982 |
| 417 | Powder River Oil | Golden, CO 80401 | Oil & Gas Operator | Sep 2018 |
| 418 | Powder River Royalty Inc | | Oil & Gas Operator | Dec 1986 |
| 419 | Powerline Energy Corporation | Arlington, TX 76015 | Oil & Gas Operator | Jul 2026 |
| 420 | PRB Oil & Gas Inc | Denver, CO 80202 | Gas Operator | Jul 2008 |
| 421 | Preferred Pipeline Corp. | Victoria, TX 77902 | Oil & Gas Operator | Jun 2026 |
| 422 | Prenalta Corporation | Terrytown, NY 10591 | Oil & Gas Operator | Jan 1997 |
| 423 | Pride Energy Company An Oklahoma GP | Tulsa, OK 74170 | Oil & Gas Operator | May 2026 |
| 424 | Prima Exploration, Inc. | Denver, CO 80206 | Oil & Gas Operator | Jun 2026 |
| 425 | Propel Energy Company | | Oil Operator | Oct 1991 |
| 426 | Prospective Invest & Trad Co LTD | Tulsa, OK 74170 | Oil & Gas Operator | Aug 2005 |
| 427 | Provident Resources LTD | | Oil & Gas Operator | Dec 1986 |
| 428 | Puma Petroleum I | | Oil & Gas Operator | Dec 1988 |
| 429 | Pure Petroleum LLC | Gillette, WY 82717 | Oil & Gas Operator | Aug 2011 |
| 430 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2026 |
| 431 | Quest Operating LLC | Sheridan, WY 82801 | Gas Operator | Sep 2008 |
| 432 | Quicksilver Resources Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2018 |
| 433 | Quinoco Petroleum Inc | | Oil & Gas Operator | Dec 1990 |
| 434 | Quintana Petroleum Corporation | Denver, CO 80265 | Oil & Gas Operator | Mar 2026 |
| 435 | Rainbow Oil Company | | Oil & Gas Operator | Aug 1999 |
| 436 | Rainbow Resources, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Aug 2007 |
| 437 | Ranch Oil Company | West Linn, OR 97068 | Oil & Gas Operator | Jun 2026 |
| 438 | Ranger Holdings Co | | Oil & Gas Operator | Jul 1993 |
| 439 | RB Operating Company | Shawnee, OK 74802-1488 | Oil & Gas Operator | Apr 2015 |
| 440 | Reading & Bates Petroleum | | Oil & Gas Operator | Apr 1989 |
| 441 | Red Rock Resources Corporation | Greenwood VIllage, CO 80111 | Oil & Gas Operator | May 2026 |
| 442 | Red Tiger Oil & Gas LLC | Gillette, WY 82718 | Oil & Gas Operator | May 2026 |
| 443 | Redbud E & P, Inc. | Giddings, TX 78942 | Oil & Gas Operator | Jul 2026 |
| 444 | Redstone Resources Inc | Newcastle, WY 82701 | Gas Operator | Dec 2010 |
| 445 | Reef Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | Feb 2007 |
| 446 | Reliance Resources Inc | Houston, TX 77007 | Gas Operator | Jun 2012 |
| 447 | Renor Exploration | Englewood, CO 80111 | Oil Operator | Feb 2001 |
| 448 | Reserve Oil & Gas Company | | Oil & Gas Operator | Jul 1981 |
| 449 | Resolute Wyoming Inc | Denver, CO 80203 | Oil & Gas Operator | May 2018 |
| 450 | Resource Enterprises Inc | Salt Lake City, UT 84108 | Gas Operator | Dec 1990 |
| 451 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 452 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |
| 453 | Richardson Operating Company | Denver, CO 80237 | Oil & Gas Operator | May 2026 |
| 454 | Ridge Energy Partners LLC | Casper, WY 82601 | Oil Operator | Dec 2018 |
| 455 | Rim Operating, Inc. | Englewood, CO 80112 | Oil & Gas Operator | Jul 2026 |
| 456 | Rme Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Nov 2016 |
| 457 | Rochelle Oil & Gas | Gillette, WY 82717 | Oil & Gas Operator | Mar 2024 |
| 458 | Rock Creek Resources LLC | Englewood, CO 80112 | Oil & Gas Operator | Dec 2021 |
| 459 | Rock Oil Corporation | Lawrence, KS 66046 | Oil Operator | Oct 2004 |
| 460 | Rockies Resources Holdings LLC | Lakewood, CO 80228 | Oil & Gas Operator | May 2026 |
| 461 | Rocky Mountain Gas Inc | Sheridan, WY 82801 | Gas Operator | Nov 2009 |
| 462 | Roemer Oil Company | Denver, CO 80202 | Oil & Gas Operator | Nov 1998 |
| 463 | Roff Operating Company LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2026 |
| 464 | Royal Resources Exploration | | Oil & Gas Operator | Mar 1984 |
| 465 | Ruby Drilling Company Inc | Gillette, WY 82718 | Oil Operator | Oct 2007 |
| 466 | Sabine Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Jul 1996 |
| 467 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 468 | Saga Petroleum LLC Of Colorado | Norman, OK 73072 | Oil & Gas Operator | Jul 2026 |
| 469 | Sage Butte PRB Operating, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2026 |
| 470 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 471 | Samson Oil & Gas USA Inc | Denver, CO 80202 | Oil & Gas Operator | May 2026 |
| 472 | Samson Resources Company LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2021 |
| 473 | San Marco Petroleum Inc | Denver, CO 80293 | Oil & Gas Operator | Apr 2026 |
| 474 | Sands Oil Company Inc | Billings, MT 59103 | Oil & Gas Operator | May 2026 |
| 475 | Santa Rosa Petroleum LLC | Recluse, WY 82725 | Oil & Gas Operator | Apr 2026 |
| 476 | Scana Petroleum Resources Inc | Houston, TX 77002 | Oil & Gas Operator | Jun 2013 |
| 477 | Schmid Properties, Inc. | Hico, TX 76457 | Oil & Gas Operator | Jul 2026 |
| 478 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 479 | Seer Operating LLC | Sheridan, WY 82801 | Oil & Gas Operator | Oct 2016 |
| 480 | Seguro Oil & Gas Inc | | Oil Operator | Jul 1992 |
| 481 | Seven Sisters Oil & Gas LLC | Casper, WY 82602 | Oil & Gas Operator | Jan 2022 |
| 482 | Shar Alan Oil Company | | Oil & Gas Operator | Oct 2005 |
| 483 | Sharkey Well Service Inc | | Oil Operator | Dec 2023 |
| 484 | Shenandoah Energy Inc | Denver, CO 80265-1050 | Oil & Gas Operator | Dec 2014 |
| 485 | Sheridan Production Company, LLC | Houston, TX 77056 | Oil & Gas Operator | Apr 2026 |
| 486 | Siegfried R H Inc | Tulsa, OK 74104 | Oil & Gas Operator | Mar 2008 |
| 487 | Simasko Production Co | Denver, CO 80204 | Oil & Gas Operator | Nov 1997 |
| 488 | Six Bar Oil LLC | Pine Haven, WY 82721 | Oil & Gas Operator | May 2026 |
| 489 | Skinner Oil & Gas LLC | Gillette, WY 82717 | Oil & Gas Operator | Jan 2024 |
| 490 | Skull Creek A LLC | Douglas, WY 82633 | Oil & Gas Operator | Feb 2026 |
| 491 | Skyline Oil Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Jan 1987 |
| 492 | Slaughter J M Oil Company | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2001 |
| 493 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2026 |
| 494 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2026 |
| 495 | Smith Conley P Operating Co | Eglewood, CO 80112-3640 | Oil & Gas Operator | Jun 2000 |
| 496 | Smokey Oil Company Inc | Casper, WY 82601 | Oil & Gas Operator | Dec 1996 |
| 497 | Snowy Owl LLC | Gillette, WY 82717 | Oil & Gas Operator | May 2026 |
| 498 | Snyder Oil Corporation | Houston, TX 77024 | Oil & Gas Operator | Mar 2008 |
| 499 | Sonat Exploration Co. | Houston, TX 77251 | Oil & Gas Operator | Dec 2021 |
| 500 | South Coast Oil Corporation | Boulder, CO 80302 | Oil & Gas Operator | Oct 2015 |