| 501 | Kaiser-Francis Oil Company | Tulsa, OK 74121 | Oil & Gas Operator | Jul 2025 |
| 502 | Kana Resources, Inc. | Dallas, TX 75243 | Oil & Gas Operator | Aug 2003 |
| 503 | Katsco Energy, Inc. | Round Rock, TX 78664 | Oil & Gas Operator | Jul 2025 |
| 504 | Kem Energy, Inc. | Katy, TX 77450 | Oil & Gas Operator | Jul 2025 |
| 505 | Kennedy, R. R. Production, Inc. | MC Camey, TX 79752 | Oil & Gas Operator | Jul 2025 |
| 506 | Kerogen Texas Energy Op LLC | Houston, TX 77060 | Oil & Gas Operator | Feb 2018 |
| 507 | Kerr-McGee Corporation | Dallas, TX 75380 | Oil & Gas Operator | Apr 2025 |
| 508 | Kerr-McGee Oil & Gas Onshore LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2017 |
| 509 | Kerr-McGee Oil & Gas Onshore LP | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 510 | Keystone Petroleum NM LLC | Irving, TX 75039 | Oil & Gas Operator | Jan 2016 |
| 511 | Killer Rabbit Fields LLC | Monahans, TX 79756 | Oil & Gas Operator | Jul 2025 |
| 512 | Kimball Production Co. | Houston, TX 77042 | Oil & Gas Operator | Jul 2002 |
| 513 | Kimbrough Oil Company | Iraan, TX 79744 | Oil Operator | Jul 2025 |
| 514 | Kimbrough, D. E. | Iraan, TX 79744 | Oil & Gas Operator | Jul 2025 |
| 515 | Kimsey, Roy E., Jr. | Midland, TX 79701 | Oil & Gas Operator | May 2018 |
| 516 | Kinder Morgan Production Co LLC | Midland, TX 79705 | Oil & Gas Operator | Jul 2025 |
| 517 | Kinder Morgan Production Co LP | Midland, TX 79701 | Oil & Gas Operator | Jul 2007 |
| 518 | Kinder Morgan Sacroc LP | Snyder, TX 79549 | Oil & Gas Operator | Dec 2003 |
| 519 | King Oil & Resources Co | Midland, TX 79705 | Oil & Gas Operator | Jul 2025 |
| 520 | Kinlaw Oil Corporation | Dallas, TX 75380 | Oil & Gas Operator | Jul 2025 |
| 521 | Kirkpatrick Oil Company | Nichols Hill, OK 73116 | Oil & Gas Operator | Jul 2025 |
| 522 | KLM Petroleum Corp. | Midland, TX 79705 | Oil & Gas Operator | Jul 2025 |
| 523 | Kneupper Oil, LLC | MC Camey, TX 79752 | Oil & Gas Operator | Jul 2025 |
| 524 | Kojo Energy, Inc. | Odessa, TX 79760 | Oil & Gas Operator | Jul 2025 |
| 525 | Kokomo Oil Company | Houston, TX 77227 | Oil & Gas Operator | Apr 1998 |
| 526 | KRF Production Company LLC | Houston, TX 77269 | Oil & Gas Operator | Jul 2025 |
| 527 | Kstone Energy, LLC | Oklahoma City, OK 73106 | Oil Operator | Jul 2025 |
| 528 | KZ Global Energy, LLC | Houston, TX 77042 | Oil & Gas Operator | Jul 2025 |
| 529 | L.C.S. Production Company | Abilene, TX 79608 | Oil & Gas Operator | Jul 2025 |
| 530 | Lacy Operations, LTD. | Longview, TX 75606 | Oil & Gas Operator | Oct 2012 |
| 531 | Laguna Petroleum Corporation | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 532 | Lakehills Production, Inc. | Austin, TX 78701 | Oil & Gas Operator | Jul 2025 |
| 533 | Lakeshore Operating, LLC | Wichita, KS 67203 | Oil & Gas Operator | Jul 2025 |
| 534 | Lamb, James L., Jr. | Austin, TX 78750 | Oil & Gas Operator | Mar 2016 |
| 535 | Laneer Resources Company | Abilene, TX 79608 | Oil & Gas Operator | Jul 2025 |
| 536 | Laredo Petroleum Inc | Tulsa, OK 74120 | Oil & Gas Operator | Mar 2023 |
| 537 | Lario Oil & Gas Company | Odessa, TX 79762 | Oil & Gas Operator | Jul 2025 |
| 538 | Las Animas Production Company | Midland, TX 79705 | Oil & Gas Operator | Mar 1995 |
| 539 | Last Mile Production, LLC | Austin, TX 78746 | Oil & Gas Operator | Jul 2025 |
| 540 | Latex Petroleum Corp. | Houston, TX 77090 | Oil & Gas Operator | Aug 2012 |
| 541 | Lavanco Energy, LTD. | San Angelo, TX 76906 | Oil & Gas Operator | Feb 2024 |
| 542 | Lawrence, C. F. & Assoc. Inc. | Lubbock, TX 79401 | Oil & Gas Operator | Jul 2025 |
| 543 | LCX Energy, LLC | Midland, TX 79701 | Oil & Gas Operator | Jan 2010 |
| 544 | Lee Production Co. | Monahans, TX 79756 | Oil & Gas Operator | Jul 2025 |
| 545 | Legacy Reserves Operating LP | Denver, CO 80201 | Oil & Gas Operator | Jul 2025 |
| 546 | Leonard Brothers Operating Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Jul 2025 |
| 547 | Letwin & Kallison | Fort Worth, TX 76107 | Oil & Gas Operator | Jun 2004 |
| 548 | Lillis, Michael D. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 549 | Limark Corporation | Midland, TX 79702 | Oil & Gas Operator | Dec 2003 |
| 550 | Limestone Exploration, LLC | Midland, TX 79702 | Oil & Gas Operator | Aug 2011 |
| 551 | Lindenmuth & Associates Inc | Austin, TX 78703 | Oil & Gas Operator | Aug 2024 |
| 552 | Linn Operating LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 553 | Linn Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2017 |
| 554 | Lion Production, Inc. | Midland, TX 79702 | Oil & Gas Operator | Mar 2006 |
| 555 | Live Oak Gas Company | Dallas, TX 75251 | Oil & Gas Operator | Jul 2025 |
| 556 | Llano Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2025 |
| 557 | Locin Oil Corporation | Katy, TX 77494 | Oil & Gas Operator | Jul 2025 |
| 558 | Lomak Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 1998 |
| 559 | Lone Star Oil & Gas | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 560 | Longfellow Energy, LP | Dallas, TX 75225 | Oil & Gas Operator | Jul 2025 |
| 561 | Lovelady, I. W. | Albuquerque, NM 87111 | Oil & Gas Operator | Jan 1996 |
| 562 | Lpes, Inc. | Provo, UT 84604 | Oil & Gas Operator | Nov 2018 |
| 563 | LRR Pecos Valley, LLC | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 564 | LT Oil Company | Midland, TX 79705 | Oil & Gas Operator | Jul 2025 |
| 565 | LTS Oil & Gas | Lubbock, TX 79424 | Oil & Gas Operator | Jul 2025 |
| 566 | LTS Oil & Gas A | Lubbock, TX 79424 | Oil & Gas Operator | Jul 2025 |
| 567 | Luxe Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2021 |
| 568 | Lyco Energy Corporation | Dallas, TX 75206 | Oil & Gas Operator | Jun 2015 |
| 569 | Lynx Energy Company, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Mar 2008 |
| 570 | Lynx Operating Co., Inc. | Dallas, TX 75206 | Oil & Gas Operator | Jul 2025 |
| 571 | M & G Oil Company | Marble Falls, TX 78654 | Oil & Gas Operator | Jul 2025 |
| 572 | M-T Petroleum, Inc. | Andrews, TX 79714 | Oil & Gas Operator | Mar 2008 |
| 573 | M.A.R.S. Energy | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 574 | Magnum Oilfield Services LLC | Bakersfield, CA 93309 | Oil Operator | Jul 2025 |
| 575 | Main Energy, Inc. | Houston, TX 77079 | Oil & Gas Operator | May 2009 |
| 576 | Mammoth Exploration LLC | Midland, TX 79701 | Oil & Gas Operator | Jul 2023 |
| 577 | Manning, Jack | Odessa, TX 79760 | Oil & Gas Operator | Dec 2003 |
| 578 | Manti Tarka Permian Op, LLC | Houston, TX 77056 | Oil & Gas Operator | Jul 2025 |
| 579 | Manzano Oil Corporation | Roswell, NM 88202 | Oil & Gas Operator | Feb 2005 |
| 580 | Maralo, Inc. | Midland, TX 79702 | Oil & Gas Operator | Dec 1998 |
| 581 | Maralo, LLC | Midland, TX 79702 | Oil & Gas Operator | Mar 2008 |
| 582 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | May 2025 |
| 583 | Marshall & Winston, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2025 |
| 584 | Martin Foree Operating, LLC | Royse City, TX 75189 | Oil & Gas Operator | Jul 2025 |
| 585 | Mas Operating Co. | Midland, TX 79710 | Oil & Gas Operator | Jul 2025 |
| 586 | Matador Operating Company | Dallas, TX 75240 | Oil & Gas Operator | Jul 2003 |
| 587 | Maverick Properties, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Sep 1994 |
| 588 | Maynard Oil Co. | Denver, CO 80202 | Oil & Gas Operator | Sep 2004 |
| 589 | MBR Resources, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Jul 2025 |
| 590 | MBX Operating LLC | Houston, TX 77007 | Oil & Gas Operator | Jul 2025 |
| 591 | McCabe Energy, Inc. | Midland, TX 79702 | Oil & Gas Operator | Aug 2009 |
| 592 | McCamey Oil And Gas LLC | MC Camey, TX 79752 | Oil Operator | Jul 2025 |
| 593 | McClure Oil Company, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 594 | McClymond, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Jul 2001 |
| 595 | McCurdy Oil Co. | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2025 |
| 596 | McDaniel Company, Inc., The | Dallas, TX 75230 | Oil & Gas Operator | Jul 2025 |
| 597 | McDaniel Oil Co. | Marble Falls, TX 78654 | Oil & Gas Operator | Jul 2025 |
| 598 | McDaniel, Willard | Iraan, TX 79744 | Oil & Gas Operator | Nov 2004 |
| 599 | McDaniel, Willard Jr. Oil Co. | Marble Falls, TX 78654 | Oil & Gas Operator | Mar 2005 |
| 600 | McDonald Production | Lubbock, TX 79408 | Oil & Gas Operator | Mar 2003 |