| 501 | Hollub Production Company | Seguin, TX 78156 | Oil & Gas Operator | Jul 2000 |
| 502 | Hollub, Lambert Drilling Company | Seguin, TX 78155 | Oil & Gas Operator | Apr 2025 |
| 503 | Holly Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Nov 2008 |
| 504 | Holmac Oil Company | Hobbs, NM 88240 | Oil & Gas Operator | May 1996 |
| 505 | Holmes Exploration, LLC | Tulsa, OK 74136 | Oil & Gas Operator | Jun 2015 |
| 506 | Holson Well Service | Albany, TX 76430 | Oil & Gas Operator | Apr 2025 |
| 507 | Holt Brothers | Gruver, TX 79040 | Gas Operator | Apr 2025 |
| 508 | Holt Oil And Cattle LLC | Bedias, TX 77831 | Oil & Gas Operator | Apr 2025 |
| 509 | Hombre Oil Co., LTD. | Tyler, TX 75713 | Oil & Gas Operator | Apr 2021 |
| 510 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Apr 2025 |
| 511 | Home-Stake Oil & Gas Company | Plano, TX 75093 | Oil & Gas Operator | Feb 2025 |
| 512 | Home-Stake Royalty Corp., The | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2014 |
| 513 | Homeplace Oil And Gas | Caldwell, TX 77836 | Oil & Gas Operator | Feb 2021 |
| 514 | Hominy Consulting, LLC | Canadian, TX 79014 | Oil & Gas Operator | Apr 2025 |
| 515 | Hondo Drilling Company | Midland, TX 79702 | Oil & Gas Operator | Nov 1996 |
| 516 | Honeck Oil Company | Austin, TX 78716 | Oil & Gas Operator | Mar 2008 |
| 517 | Honeck Oil Company, LP | Austin, TX 78716 | Oil & Gas Operator | Dec 2010 |
| 518 | Hood, J. F. | Holliday, TX 76366 | Oil & Gas Operator | Apr 2010 |
| 519 | Hood, J. Frank, Jr. | Arlington, TX 76006 | Oil & Gas Operator | Apr 2025 |
| 520 | Hood, Joe B. | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2008 |
| 521 | Hooks & Hooks | Abilene, TX 79608 | Oil & Gas Operator | Feb 1999 |
| 522 | Hooper & Sons Investments Co.Inc | Tenaha, TX 75974 | Gas Operator | Nov 1997 |
| 523 | Hooper, DR. Oil & Royalty Co. | Conroe, TX 77304 | Oil & Gas Operator | Sep 1999 |
| 524 | Hootkins, Seymour G. | Archer City, TX 76351 | Oil & Gas Operator | Apr 1997 |
| 525 | Hoover Petroleum Company, LLC | Midland, TX 79701 | Oil Operator | Apr 2025 |
| 526 | Hopco Operating, Inc. | Stafford, TX 77497 | Oil & Gas Operator | Dec 2016 |
| 527 | Hope Energy, L.L.C. | Snyder, TX 79549 | Oil & Gas Operator | Apr 2025 |
| 528 | Hope Production, Inc. | Edinburg, TX 78540 | Oil & Gas Operator | Jan 2000 |
| 529 | Hopewell Operating, Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Apr 2025 |
| 530 | Hopkins Engineering, Inc. | Houston, TX 77046 | Oil & Gas Operator | Sep 1996 |
| 531 | Hopkins, T. M. Operating Co. | Kilgore, TX 75663 | Oil & Gas Operator | Apr 2025 |
| 532 | Hopper, Harlan | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 533 | Hopper, Thornton Co. | Midland, TX 79702 | Oil & Gas Operator | Apr 2025 |
| 534 | Horadam, Henry L. | Victoria, TX 77905 | Oil & Gas Operator | Oct 2008 |
| 535 | Horan, Ken L. | Cross Plains, TX 76443 | Gas Operator | May 2002 |
| 536 | Horansky Burrell Revocable Trust | Wichita Falls, TX 76309 | Oil Operator | Apr 2025 |
| 537 | Horany, Ray & Ernest | Olney, TX 76374 | Oil & Gas Operator | May 2002 |
| 538 | Horizon Energy | Vergas, MN 56587 | Oil & Gas Operator | Apr 2025 |
| 539 | Horizon Exploration Company | Houston, TX 77019 | Oil & Gas Operator | Aug 2002 |
| 540 | Horizon Exploration Services | El Paso, TX 79922 | Oil Operator | Apr 2025 |
| 541 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 542 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 543 | Horizon Oil & Gas Co. | Dallas, TX 75221 | Oil & Gas Operator | Jan 2005 |
| 544 | Horizon Prod. And Operating, LLC | Houston, TX 77019 | Oil & Gas Operator | Apr 2025 |
| 545 | Horizon Ridge Oil Company | Austin, TX 78738 | Oil Operator | Apr 2025 |
| 546 | Horizon Well Services, Inc. | Abilene, TX 79604 | Oil & Gas Operator | Apr 2025 |
| 547 | Horn Energy | Eastland, TX 76448 | Oil & Gas Operator | Apr 2025 |
| 548 | Horn, Tom D. | Pampa, TX 79066 | Gas Operator | Nov 2013 |
| 549 | Horn, W. J. | Graham, TX 76450 | Oil & Gas Operator | Oct 2004 |
| 550 | Horne & Moore Oil Co. | Holliday, TX 76366 | Oil & Gas Operator | Feb 2001 |
| 551 | Horseshoe Production, LLC | Bryson, TX 76427 | Oil Operator | Apr 2025 |
| 552 | Horst Energy LLC | Fort Worth, TX 76124 | Oil & Gas Operator | Jun 2019 |
| 553 | Hosford Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 1994 |
| 554 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 555 | Houchin, O. E. Inc. | Olney, IL 62450 | Oil & Gas Operator | Feb 1997 |
| 556 | Houghton Oil & Gas, Inc. | Midland, TX 79701 | Oil & Gas Operator | Mar 2009 |
| 557 | Houston Energy Operating, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jul 2020 |
| 558 | Houston Energy, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 559 | Houston Expl. & Prod. Co., Inc. | Austin, TX 78746 | Oil & Gas Operator | Aug 2003 |
| 560 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 561 | Houston Gulf Energy Corporation | The Woodlands, TX 77380 | Oil & Gas Operator | Apr 2025 |
| 562 | Houston Hydrocarbons, Inc. (A) | Houston, TX 77042 | Oil & Gas Operator | Sep 2004 |
| 563 | Houston Oil & Gas Company, Inc. | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 564 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 565 | Houston Oil Prod Enterprises,Inc | Houston, TX 77006 | Oil & Gas Operator | Apr 2025 |
| 566 | Houston Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 567 | Houston Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Apr 2025 |
| 568 | Houston Resources Corp. | Houston, TX 77002 | Oil & Gas Operator | Apr 2003 |
| 569 | Houtchens, D. D. | Gainesville, TX 76240 | Oil & Gas Operator | Apr 2025 |
| 570 | Houtchens, DD & Anna D LVNG TRST | Garland, TX 75043 | Oil Operator | Apr 2025 |
| 571 | Hovgard & Fitzgerald | Abilene, TX 79608 | Oil & Gas Operator | Mar 1996 |
| 572 | Howard Exploration, Inc. | Houston, TX 77069 | Oil & Gas Operator | Apr 2025 |
| 573 | Howard Operating Co. | Saint Jo, TX 76265 | Oil & Gas Operator | Apr 2025 |
| 574 | Howard, Anthony E. F. | Tyler, TX 75701 | Oil & Gas Operator | Jun 2001 |
| 575 | Howard, Douglas J. | Houston, TX 77070 | Oil & Gas Operator | Mar 2008 |
| 576 | Howell & Sandlin, Inc. | Marshall, TX 75671 | Oil & Gas Operator | Jan 2001 |
| 577 | Howell Crane & Rigging, Inc. | San Antonio, TX 78220 | Oil Operator | Apr 2025 |
| 578 | Howell Drilling, Inc. | San Antonio, TX 78230 | Oil & Gas Operator | Aug 2003 |
| 579 | Howell Oil & Gas, Inc. | Marshall, TX 75671 | Oil & Gas Operator | Oct 2019 |
| 580 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 581 | Howell, Ray | Breckenridge, TX 76424 | Oil & Gas Operator | May 1998 |
| 582 | Howitzer Operating, LLC | Dallas, TX 75380 | Oil Operator | Apr 2025 |
| 583 | Howle Operating Account, Inc. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 1999 |
| 584 | Howle, A.G. | Breckenridge, TX 76424 | Oil & Gas Operator | Dec 2011 |
| 585 | HPC Energy LLC | Midland, TX 79703 | Oil & Gas Operator | Aug 2013 |
| 586 | HPC Operating, Inc. | Dallas, TX 75379 | Oil & Gas Operator | Mar 2008 |
| 587 | HPPC, Inc. | Midland, TX 79701 | Oil & Gas Operator | Feb 2023 |
| 588 | HR Petroleum | Corpus Chrsti, TX 78413 | Oil & Gas Operator | Apr 1998 |
| 589 | HRB Oil | Houston, TX 77042 | Oil & Gas Operator | Oct 1998 |
| 590 | HRB Operating Company Inc | Bridgeport, TX 76426 | Oil & Gas Operator | Apr 2025 |
| 591 | Hrbacek Oil Corp. | La Grange, TX 78945 | Oil & Gas Operator | Feb 2004 |
| 592 | HRF Exploration & Production LLC | Gaylord, MI 49734-0160 | Gas Operator | Apr 2025 |
| 593 | HRF Exploration & Production,Inc | Denver, CO 80237 | Oil & Gas Operator | Mar 2009 |
| 594 | HRH Energy Group Incorporated | Carrollton, TX 75006 | Oil & Gas Operator | Nov 2009 |
| 595 | Hronek, Kenneth | Caldwell, TX 77836 | Oil & Gas Operator | Apr 2025 |
| 596 | Hrubetz Oil Co. | Dallas, TX 75225 | Oil Operator | Sep 1986 |
| 597 | Hrubetz Operating Company | Dallas, TX 75225 | Oil & Gas Operator | Feb 1999 |
| 598 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2005 |
| 599 | HTR Operating Co., Inc. | Hurst, TX 76053 | Oil & Gas Operator | Apr 2025 |
| 600 | Hub-Cap Oil Company | Arlington, TX 76016 | Oil & Gas Operator | Dec 2013 |