| 401 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Jun 2025 |
| 402 | Maverick Oil Co. | Richland, TX 76681 | Oil Operator | Jul 2025 |
| 403 | McCartney Engineering LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | May 2025 |
| 404 | McCoy Petroleum Corporation | Wichita, KS 67207 | Oil & Gas Operator | Jun 2025 |
| 405 | McElvain Energy Inc | Denver, CO 80265 | Oil & Gas Operator | Nov 2019 |
| 406 | McLane Trust* Dixie | | Gas Operator | May 2025 |
| 407 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 408 | McWhinney Holding Company LLLP | | Oil & Gas Operator | Mar 2021 |
| 409 | MDS Energy Development LLC | | Oil & Gas Operator | May 2025 |
| 410 | Medicine Bow Operating Company | Houston, TX 77002 | Oil & Gas Operator | Apr 2014 |
| 411 | Mendell Finisterre II LLC | | Oil & Gas Operator | Jun 2017 |
| 412 | Mendell Niobrara LLC | | Oil & Gas Operator | Apr 2017 |
| 413 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2025 |
| 414 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | May 2025 |
| 415 | Mesa Energy Partners LLC | | Oil & Gas Operator | Sep 2015 |
| 416 | Mesa Hydrocarbons LLC | | Oil & Gas Operator | Sep 2003 |
| 417 | Messer LLC | | Gas Operator | Jul 2024 |
| 418 | Mid-Con Energy Operating, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jun 2025 |
| 419 | Mineral Resources, Incorporated | Lewisville, TX 75029 | Oil & Gas Operator | Jul 2025 |
| 420 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 421 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Jun 2016 |
| 422 | Monago Operating Inc | | Oil & Gas Operator | Mar 2017 |
| 423 | Monahan* Rex Family Trust | | Oil & Gas Operator | Sep 2010 |
| 424 | Monument Gas Marketing Inc | | Oil & Gas Operator | May 2025 |
| 425 | Monument Global Resources Inc | Dallas, TX 75243 | Oil & Gas Operator | Jan 2025 |
| 426 | Morning Gun Exploration LLC | | Oil Operator | Oct 2021 |
| 427 | Morningstar Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2025 |
| 428 | Mountain Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Jan 2016 |
| 429 | MRD Operating LLC | | Oil & Gas Operator | Dec 2016 |
| 430 | Mull Drilling Company | Wichita, KS 67206 | Oil & Gas Operator | May 2025 |
| 431 | Murchison Oil & Gas Inc | Plano, TX 75024 | Oil & Gas Operator | Mar 2024 |
| 432 | Murchison Trusts | | Gas Operator | Sep 2003 |
| 433 | Murfin Drilling Company Inc | Wichita, KS 67202 | Oil & Gas Operator | Jun 2025 |
| 434 | Mustang Resources LLC | Houston, TX 77256 | Oil & Gas Operator | May 2025 |
| 435 | Mystique Resources Company | Aurora, CO 80016 | Oil & Gas Operator | Feb 2023 |
| 436 | Nance Petroleum Corporation | Billings, MT 59103-7168 | Oil & Gas Operator | Nov 2007 |
| 437 | Nanke Energy LLC | Westminster, CO 80234 | Oil & Gas Operator | Apr 2025 |
| 438 | National Fuel Corporation | Greenwood VIllage, CO 80111 | Oil & Gas Operator | May 2025 |
| 439 | Natural Resource Group Inc | | Oil & Gas Operator | Jan 2024 |
| 440 | New Frontier Energy Inc | | Gas Operator | Mar 2010 |
| 441 | New Horizon Exploration, Inc. | Richardson, TX 75081 | Oil & Gas Operator | Jun 2006 |
| 442 | Newell Energy LTD | | Gas Operator | Nov 2021 |
| 443 | Newfield Production Company | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Jul 2022 |
| 444 | Nickel Road Operating LLC | | Oil & Gas Operator | Sep 2024 |
| 445 | Nielson & Associates Inc | Cody, WY 82414 | Oil & Gas Operator | Feb 2016 |
| 446 | Nighthawk Production LLC | | Oil & Gas Operator | Jun 2018 |
| 447 | Niobrara Illuminating Gas Associates LLC | | Oil & Gas Operator | Oct 2009 |
| 448 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | Jul 2025 |
| 449 | Noble Energy Production Inc | Houston, TX 77067 | Oil & Gas Operator | Jul 2025 |
| 450 | Nonsuch Natural Gas Inc | Naples, FL 34108 | Oil & Gas Operator | May 2025 |
| 451 | Norstar Petroleum Inc | Englewood, CO 80112 | Oil & Gas Operator | Mar 2025 |
| 452 | North American Resources Company | Billings, MT 59101 | Oil & Gas Operator | Dec 2019 |
| 453 | North Shore Exploration & Prod LLC | Broomfield, CO 80021 | Oil & Gas Operator | May 2025 |
| 454 | Northern Michigan Oil & Gas Corporation | | Oil & Gas Operator | Dec 2024 |
| 455 | Northstar Gas Company Inc | | Oil & Gas Operator | Jan 2016 |
| 456 | Nova Energy Inc | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 457 | Nuevida Resources LLC | Dallas, TX 75235 | Gas Operator | May 2025 |
| 458 | Nylund* J. W. | | Oil Operator | Jul 2000 |
| 459 | O'Brien Energy Resources Corp | Portsmouth, NH 03801 | Oil & Gas Operator | Jul 2025 |
| 460 | Ocean Energy Inc Ndba Devon Louisiana Corp | | Oil & Gas Operator | Jul 2001 |
| 461 | Ogris Operating LLC | | Gas Operator | May 2025 |
| 462 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 463 | Oilfield Salvage & Service Company | Littleton, CO 80120 | Oil & Gas Operator | May 2025 |
| 464 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 465 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 466 | Organic Energy Company LLC | | Oil & Gas Operator | Jun 2025 |
| 467 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 468 | Orr Energy LLC | | Oil & Gas Operator | Nov 2012 |
| 469 | Overland Resources LLC | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Jul 2019 |
| 470 | Own Resources Operating LLC | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 471 | Oxbow Properties Inc | Centennial, CO 80122-1422 | Oil & Gas Operator | Jan 2025 |
| 472 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 473 | Oxy USA WTP LP | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 474 | P & M Petroleum Management LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2021 |
| 475 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | Jul 2025 |
| 476 | Padco LLC | | Oil & Gas Operator | May 2025 |
| 477 | Painted Pegasus Petroleum LLC | | Oil & Gas Operator | Jul 2024 |
| 478 | Paladin Energy Partners LLC | | Oil & Gas Operator | Dec 2006 |
| 479 | Pan American Petroleum Corp | | Oil & Gas Operator | Jan 2008 |
| 480 | Pancanadian Energy Resources Inc | | Oil & Gas Operator | Dec 2004 |
| 481 | Pape Oilfield Service Inc | | Oil & Gas Operator | Jul 2018 |
| 482 | Par Pacific Holdings Inc | | Oil & Gas Operator | Apr 2015 |
| 483 | Patara Oil & Gas LLC | Dallas, TX 75219 | Oil & Gas Operator | Mar 2018 |
| 484 | Patina Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2016 |
| 485 | PCR Operating LLC | | Oil & Gas Operator | Jul 2024 |
| 486 | PDC Energy Inc | Denver, CO 80203 | Oil & Gas Operator | May 2025 |
| 487 | Peakview Operating Company, LLC | | Oil & Gas Operator | Apr 2025 |
| 488 | Pelican Hill Oil & Gas Inc | Carlsbad, CA 92010 | Oil & Gas Operator | May 2013 |
| 489 | Petcon Associates LTD | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 490 | Peterson Energy Operating Inc | Loveland, CO 80537 | Oil & Gas Operator | Jun 2025 |
| 491 | Petra Oleum Corp. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 492 | Petro Mex Resources | | Oil & Gas Operator | Apr 2025 |
| 493 | Petro Operating Company LLC | | Oil & Gas Operator | May 2025 |
| 494 | Petro-Canada Resources (USA) Inc | Denver, CO 80202-472 | Oil & Gas Operator | Feb 2010 |
| 495 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 496 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 497 | Petroleum Energy Corp | | Oil & Gas Operator | Aug 2012 |
| 498 | Petroleum Exploration Company LTD Dba Petex | | Oil Operator | May 2025 |
| 499 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 500 | Petroleum Management LLC | Platteville, CO 80651 | Oil & Gas Operator | May 2011 |