| 501 | Arrington CJM, Inc. | Canadian, TX 79014 | Oil & Gas Operator | Nov 2021 |
| 502 | Arrington Oil&Gas Operating LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 503 | Arrington Production Company | Pampa, TX 79066 | Oil & Gas Operator | Oct 2025 |
| 504 | Arrington,David H. Oil & Gas,Inc | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 505 | Arriola Operating & Consltg Inc. | Dallas, TX 75248 | Oil Operator | Oct 2025 |
| 506 | Arris Operating Company LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2016 |
| 507 | Arrow Energy, Incorporated | Houston, TX 77008 | Oil & Gas Operator | Jun 2025 |
| 508 | Arrow Exploration Company | Plano, TX 75075 | Oil & Gas Operator | Dec 2004 |
| 509 | Arrow Oil & Gas, LLC | Norman, OK 73070 | Oil & Gas Operator | Oct 2025 |
| 510 | Arrow Operating Company | Dallas, TX 75231 | Oil & Gas Operator | Jun 2025 |
| 511 | Arrow Rock Energy, LLC | Houston, TX 77079 | Oil & Gas Operator | Mar 2018 |
| 512 | Arrow S Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 513 | Arrowhead Energy Exp., LLC | Baton Rouge, LA 70816 | Oil & Gas Operator | Nov 2006 |
| 514 | Arrowhead Enterprises, Inc. | Baton Rouge, LA 70816 | Oil & Gas Operator | Apr 2001 |
| 515 | Arrowhead Exploration Company | Olney, TX 76374 | Oil Operator | Dec 1995 |
| 516 | Arrowhead Operating Inc. | Argyle, TX 76226 | Oil & Gas Operator | Oct 2025 |
| 517 | Arrowhead Productions, LP | Fort Worth, TX 76109 | Oil & Gas Operator | Oct 2025 |
| 518 | Arrowhead Resources, Inc. | Fort Worth, TX 76107 | Oil & Gas Operator | Oct 2025 |
| 519 | Arrowood Production Inc | Cross Plains, TX 76443 | Oil & Gas Operator | Mar 2008 |
| 520 | Aruba Petroleum, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Jun 2025 |
| 521 | Aruba Petroleum, LTD. | Dallas, TX 75206 | Oil & Gas Operator | Aug 2003 |
| 522 | Ary, J. Kirk | Midland, TX 79708 | Oil & Gas Operator | Jun 1993 |
| 523 | Arya Resources, LLC | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 524 | Asa Oil & Gas, Inc. | Brady, TX 76825 | Oil & Gas Operator | Oct 2025 |
| 525 | Asante Operating Company, LLC | Austin, TX 78703 | Oil Operator | Oct 2025 |
| 526 | Ascent Energy, Inc | McKinney, TX 75069 | Oil & Gas Operator | Nov 2008 |
| 527 | Ascent Operating, LP | Plano, TX 75093 | Oil & Gas Operator | Aug 2008 |
| 528 | Ashbrook Oil Co. | Big Spring, TX 79721 | Oil & Gas Operator | Apr 2020 |
| 529 | Ashby, Andrew M. | Golden, CO 80401 | Oil & Gas Operator | Jul 1998 |
| 530 | Asher Resources | Boerne, TX 78006 | Oil & Gas Operator | May 2015 |
| 531 | Ashland Exploration Inc | Houston, TX 77218 | Oil & Gas Operator | Nov 2000 |
| 532 | Ashtola Exploration Company,Inc. | Amarillo, TX 79105 | Oil & Gas Operator | Oct 2025 |
| 533 | Asm Oil & Gas Company, Inc. | Dallas, TX 75367 | Oil & Gas Operator | May 2020 |
| 534 | Aspect Abundant Shale LP | Denver, CO 80203 | Oil & Gas Operator | Nov 2012 |
| 535 | Aspect Energy, LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 536 | Aspect Resources LLC | Denver, CO 80202 | Oil & Gas Operator | May 2002 |
| 537 | Aspen Energy Group, Inc. | Santa Ynez, CA 93460 | Oil & Gas Operator | Mar 2015 |
| 538 | Aspen Energy, Inc. | Seguin, TX 78156 | Oil & Gas Operator | Jul 2019 |
| 539 | Aspen Exploration, Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2012 |
| 540 | Aspen Land & Exploration Co | Tulsa, OK 74159-0335 | Oil & Gas Operator | Jul 2001 |
| 541 | Aspen Operating Company LLC | Fort Worth, TX 76116 | Oil & Gas Operator | Oct 2025 |
| 542 | Assent Energy Partners, LLC | College Sta, TX 77840 | Oil & Gas Operator | Oct 2025 |
| 543 | At Oil & Gas, LLC | Eastland, TX 76448 | Oil & Gas Operator | Oct 2025 |
| 544 | Atapco | Houston, TX 77040 | Oil & Gas Operator | Feb 1999 |
| 545 | Atasca Resources Inc | Houston, TX 77219 | Oil & Gas Operator | Oct 2025 |
| 546 | Atascosa Exploration, LLC | San Antonio, TX 78209 | Oil Operator | Apr 2020 |
| 547 | Atchley Resources, Inc. | Oklahoma City, OK 73134 | Oil & Gas Operator | Jul 2025 |
| 548 | Atco Prod. Co., Inc. | Winnie, TX 77665 | Oil & Gas Operator | Nov 2020 |
| 549 | Atex Exploration & Operating Co. | Whitesboro, TX 76273 | Oil & Gas Operator | Oct 2025 |
| 550 | Atf Petroleum Inc. | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 551 | Athanor Texas Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2002 |
| 552 | Athena Energy, Inc. | Gallatin, TN 37066 | Oil & Gas Operator | Oct 2025 |
| 553 | Athena Resources, Inc. | Dallas, TX 75248 | Oil & Gas Operator | Oct 2025 |
| 554 | Athlon Energy Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Apr 2014 |
| 555 | Athlon Fe Operating LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2015 |
| 556 | Athlon Holdings LP | Denver, CO 80202 | Oil & Gas Operator | Jan 2015 |
| 557 | Atinum Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 558 | Atinum Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 559 | Atkins Oil L.C. | Conroe, TX 77303 | Oil Operator | Oct 2025 |
| 560 | Atkinson Energy Corporation | Giddings, TX 78942 | Oil & Gas Operator | Jan 2010 |
| 561 | Atkinson Operations LLC | Three Rivers, TX 78071 | Oil Operator | Oct 2025 |
| 562 | Atkinson, Clifford III | San Antonio, TX 78217 | Oil & Gas Operator | Dec 1996 |
| 563 | Atkinson, Jim | Nocona, TX 76255 | Oil & Gas Operator | Oct 2025 |
| 564 | Atlantic & Gulf Petroleum Co. | Houston, TX 77002 | Gas Operator | Mar 1991 |
| 565 | Atlantic Exploration, LLC | Midland, TX 79701 | Oil & Gas Operator | Apr 2015 |
| 566 | Atlantic Oil Corporation | Denver, CO 80206 | Oil & Gas Operator | Dec 1982 |
| 567 | Atlantic Operating II, LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 568 | Atlantic Operating, Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 569 | Atlantic Resources Company, LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 570 | Atlantic Richfield Company | Plano, TX 75074 | Oil & Gas Operator | Dec 2016 |
| 571 | Atlantis Oil Company, Inc. | Tyler, TX 75701 | Oil & Gas Operator | Oct 2025 |
| 572 | Atlas Barnett, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2019 |
| 573 | Atlas Eagle Ford Oper Co, LLC | Fort Worth, TX 76116 | Oil & Gas Operator | May 2020 |
| 574 | Atlas Energy Corporation (Del.) | Oklahoma City, OK 73112 | Oil & Gas Operator | Oct 2025 |
| 575 | Atlas Fuel Supply, LTD. | Houston, TX 77269 | Oil Operator | Oct 2025 |
| 576 | Atlas Growth Texas, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jan 2019 |
| 577 | Atlas Oil & Gas Exploration, LLC | Cedar Park, TX 78613 | Oil & Gas Operator | Aug 2003 |
| 578 | Atlas Operating LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 579 | Atmic, Inc. | Houston, TX 77002 | Oil & Gas Operator | Jun 2008 |
| 580 | Atmos Pipeline - Texas | Dallas, TX 75240 | Oil & Gas Operator | Oct 2025 |
| 581 | Atnipp, H. L. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 582 | Atoka Energy LLC | Gainesville, TX 76241 | Oil & Gas Operator | Oct 2025 |
| 583 | Atoka Operating Permian, LLC | Addison, TX 75001 | Oil & Gas Operator | Sep 2023 |
| 584 | Atoka Operating, Inc. | Gainesville, TX 76241 | Oil & Gas Operator | Oct 2025 |
| 585 | Atp Oil & Gas Corporation | Houston, TX 77027 | Oil & Gas Operator | Jun 2008 |
| 586 | Atropos Exploration Company | Dallas, TX 75225 | Oil & Gas Operator | Oct 2025 |
| 587 | Atropos Production Corporation | Dallas, TX 75225 | Oil & Gas Operator | Oct 2025 |
| 588 | Atwa Energy Co. | Breckenridge, TX 76424 | Oil & Gas Operator | Oct 1996 |
| 589 | Atwell Oil & Gas, Inc. | Cross Plains, TX 76443 | Oil & Gas Operator | Oct 2025 |
| 590 | Atwell Technical Services, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Oct 2025 |
| 591 | Atwell, David L. | Duncan, OK 73533 | Oil & Gas Operator | Jul 2003 |
| 592 | Auburn Enterprises, Inc. | Kyle, TX 78640 | Oil & Gas Operator | Aug 2003 |
| 593 | Auden Oil Inc. | Hardin, TX 77561 | Oil Operator | Oct 2025 |
| 594 | Audrey Oil & Gas LLC | Pampa, TX 79066 | Oil & Gas Operator | Oct 2025 |
| 595 | August Oil | Plano, TX 75093 | Oil & Gas Operator | Aug 2003 |
| 596 | Augusta Oil & Gas | Abilene, TX 79604 | Oil & Gas Operator | Nov 2002 |
| 597 | Augusta Oil & Gas Inc | Abilene, TX 79604 | Oil & Gas Operator | Dec 2015 |
| 598 | Augustus Oil And Gas Corporation | Austin, TX 78731 | Oil & Gas Operator | Oct 2025 |
| 599 | Aunix Operating, LLC | Tomball, TX 77377 | Oil Operator | Oct 2025 |
| 600 | Aurivos LLC | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |