| 501 | Armor Energy LLC | Tulsa, OK 74146 | Oil & Gas Operator | Jun 2022 |
| 502 | Armor Petroleum, Inc. | Wichita Falls, TX 76308 | Oil & Gas Operator | Feb 2026 |
| 503 | Armor Resources LLC | Longview, TX 75604 | Oil & Gas Operator | Feb 2026 |
| 504 | Armour Properties | Houston, TX 77056 | Oil & Gas Operator | May 1994 |
| 505 | Armour Resource Holdings, LTD. | Houston, TX 77046 | Oil & Gas Operator | Nov 1994 |
| 506 | Armour, Widd | Graham, TX 76450 | Oil & Gas Operator | Feb 2026 |
| 507 | Armstrong Energy Corporation | Roswell, NM 88202 | Oil & Gas Operator | Dec 2025 |
| 508 | Arnold Oil Properties, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | May 2019 |
| 509 | Arnold Oil Properties, L.L.C. | Nichols Hill, OK 73116 | Oil & Gas Operator | Feb 2026 |
| 510 | Arnot Oil Company, LLC | Breckenridge, TX 76424 | Oil & Gas Operator | Feb 2026 |
| 511 | Arnot, W. G., Jr. | Breckenridge, TX 76424 | Oil & Gas Operator | Jan 2017 |
| 512 | Aroc (Texas) Inc. | Houston, TX 77090 | Oil & Gas Operator | Dec 2014 |
| 513 | Arp Barnett, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Nov 2018 |
| 514 | Arpel, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2014 |
| 515 | Arrco Operating, LLC | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Feb 2026 |
| 516 | Arrington CJM, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Nov 2021 |
| 517 | Arrington Oil&Gas Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 518 | Arrington Production Company | Pampa, TX 79066 | Oil & Gas Operator | Feb 2026 |
| 519 | Arrington,David H. Oil & Gas,Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 520 | Arriola Operating & Consltg Inc. | Dallas, TX 75248 | Oil Operator | Feb 2026 |
| 521 | Arris Operating Company LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2016 |
| 522 | Arrow Energy, Incorporated | Houston, TX 77008 | Oil & Gas Operator | Dec 2025 |
| 523 | Arrow Exploration Company | Plano, TX 75075 | Oil & Gas Operator | Dec 2004 |
| 524 | Arrow Oil & Gas, LLC | Norman, OK 73070 | Oil & Gas Operator | Feb 2026 |
| 525 | Arrow Operating Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2025 |
| 526 | Arrow Rock Energy, LLC | Houston, TX 77079 | Oil & Gas Operator | Mar 2018 |
| 527 | Arrow S Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 528 | Arrowhead Energy Exp., LLC | Baton Rouge, LA 70816 | Oil & Gas Operator | Nov 2006 |
| 529 | Arrowhead Enterprises, Inc. | Baton Rouge, LA 70816 | Oil & Gas Operator | Apr 2001 |
| 530 | Arrowhead Exploration Company | Olney, TX 76374 | Oil Operator | Dec 1995 |
| 531 | Arrowhead Operating Inc. | Argyle, TX 76226 | Oil & Gas Operator | Feb 2026 |
| 532 | Arrowhead Productions, LP | Fort Worth, TX 76109 | Oil & Gas Operator | Feb 2026 |
| 533 | Arrowhead Resources, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Feb 2026 |
| 534 | Arrowood Production Inc | Cross Plains, TX 76443 | Oil & Gas Operator | Mar 2008 |
| 535 | Artemisia Energy Texas, LLC | Houston, TX 77077 | Oil Operator | Feb 2026 |
| 536 | Aruba Petroleum, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Nov 2025 |
| 537 | Aruba Petroleum, LTD. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 538 | Ary, J. Kirk | Midland, TX 79708 | Oil & Gas Operator | Jun 1993 |
| 539 | Arya Resources, LLC | Midland, TX 79710 | Oil & Gas Operator | Feb 2026 |
| 540 | Asa Oil & Gas, Inc. | Brady, TX 76825 | Oil & Gas Operator | Feb 2026 |
| 541 | Asante Operating Company, LLC | Austin, TX 78703 | Oil Operator | Feb 2026 |
| 542 | Ascent Energy, Inc | McKinney, TX 75069 | Oil & Gas Operator | Nov 2008 |
| 543 | Ascent Operating, LP | Plano, TX 75093 | Oil & Gas Operator | Aug 2008 |
| 544 | Ashbrook Oil Co. | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2020 |
| 545 | Ashby, Andrew M. | Golden, CO 80401 | Oil & Gas Operator | Jul 1998 |
| 546 | Ashby, Julian C. Estate Of | San Antonio, TX 78239 | Gas Operator | Feb 1996 |
| 547 | Asher Resources | Boerne, TX 78006 | Oil & Gas Operator | May 2015 |
| 548 | Ashland Exploration Inc | Houston, TX 77218 | Oil & Gas Operator | Nov 2000 |
| 549 | Ashlyn Energy Corp. | Plano, TX 75086 | Gas Operator | Jul 1995 |
| 550 | Ashtola Exploration Company,Inc. | Amarillo, TX 79105 | Oil & Gas Operator | Feb 2026 |
| 551 | Asm Oil & Gas Company, Inc. | Dallas, TX 75367 | Oil & Gas Operator | May 2020 |
| 552 | Aspect Abundant Shale LP | Denver, CO 80203 | Oil & Gas Operator | Nov 2012 |
| 553 | Aspect Energy, LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2026 |
| 554 | Aspect Resources LLC | Denver, CO 80202 | Oil & Gas Operator | May 2002 |
| 555 | Aspen Energy Group, Inc. | Santa Ynez, CA 93460 | Oil & Gas Operator | Mar 2015 |
| 556 | Aspen Energy, Inc. | Seguin, TX 78156 | Oil & Gas Operator | Jul 2019 |
| 557 | Aspen Exploration, Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2012 |
| 558 | Aspen Land & Exploration Co | Tulsa, OK 74159-0335 | Oil & Gas Operator | Jul 2001 |
| 559 | Aspen Operating Company LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Feb 2026 |
| 560 | Assent Energy Partners, LLC | College Sta, TX 77840 | Oil & Gas Operator | Feb 2026 |
| 561 | Associated Operating & Explor. | Dallas, TX 75243 | Oil & Gas Operator | Feb 2026 |
| 562 | Astin Corp. | Dallas, TX 75229 | Oil & Gas Operator | Sep 1994 |
| 563 | At Oil & Gas, LLC | Eastland, TX 76448 | Oil & Gas Operator | Feb 2026 |
| 564 | Atapco | Houston, TX 77040 | Oil & Gas Operator | Feb 1999 |
| 565 | Atasca Resources, Inc. | Houston, TX 77219 | Oil & Gas Operator | Feb 2026 |
| 566 | Atascosa Exploration, LLC | San Antonio, TX 78209 | Oil Operator | Apr 2020 |
| 567 | Atchley Resources, Inc. | Oklahoma City, OK 73134 | Oil & Gas Operator | Dec 2025 |
| 568 | Atco Prod. Co., Inc. | Winnie, TX 77665 | Oil & Gas Operator | Nov 2020 |
| 569 | Aterra Exploration, LLC | San Antonio, TX 78216 | Oil & Gas Operator | Feb 2026 |
| 570 | Atex Exploration & Operating Co. | Whitesboro, TX 76273 | Oil & Gas Operator | Feb 2026 |
| 571 | Atf Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 572 | Athanor Texas Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2002 |
| 573 | Athena Energy, Inc. | Gallatin, TN 37066 | Oil & Gas Operator | Feb 2026 |
| 574 | Athena Resources, Inc. | Dallas, TX 75248 | Oil & Gas Operator | Feb 2026 |
| 575 | Athlon Energy Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2014 |
| 576 | Athlon Fe Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2015 |
| 577 | Athlon Holdings LP | Denver, CO 80202 | Oil & Gas Operator | Jan 2015 |
| 578 | Atinum Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 579 | Atinum Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2026 |
| 580 | Atkins Oil L.C. | Conroe, TX 77303 | Oil Operator | Feb 2026 |
| 581 | Atkinson Energy Corporation | Giddings, TX 78942 | Oil & Gas Operator | Jan 2010 |
| 582 | Atkinson Operations LLC | Three Rivers, TX 78071 | Oil Operator | Feb 2026 |
| 583 | Atkinson, Clifford III | San Antonio, TX 78217 | Oil & Gas Operator | Dec 1996 |
| 584 | Atkinson, Jim | Nocona, TX 76255 | Oil & Gas Operator | Feb 2026 |
| 585 | Atlantic & Gulf Petroleum Co. | Houston, TX 77002 | Gas Operator | Mar 1991 |
| 586 | Atlantic Exploration, LLC | Midland, TX 79701 | Oil & Gas Operator | Apr 2015 |
| 587 | Atlantic Oil Corporation | Denver, CO 80206 | Oil & Gas Operator | Dec 1982 |
| 588 | Atlantic Operating II, LLC | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 589 | Atlantic Operating, Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 590 | Atlantic Resources Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 591 | Atlantic Richfield Company | Houston, TX 77079 | Oil & Gas Operator | Dec 2016 |
| 592 | Atlantis Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Feb 2026 |
| 593 | Atlas Barnett, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2019 |
| 594 | Atlas Eagle Ford Oper Co, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | May 2020 |
| 595 | Atlas Energy Corporation (Del.) | Oklahoma City, OK 73112 | Oil & Gas Operator | Feb 2026 |
| 596 | Atlas Fuel Supply, LTD. | Houston, TX 77269 | Oil Operator | Feb 2026 |
| 597 | Atlas Growth Texas, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2019 |
| 598 | Atlas Oil & Gas Exploration, LLC | Cedar Park, TX 78613 | Oil & Gas Operator | Aug 2003 |
| 599 | Atlas Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Feb 2026 |
| 600 | Atmic, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jun 2008 |