| 12401 | Hallador Petroleum LLP | Denver, CO 80264 | Oil & Gas Operator | Feb 2019 |
| 12402 | Hallar Enterprises, Inc. | | Oil Operator | Oct 2007 |
| 12403 | Hallco Petroleum Inc | Oklahoma City, OK 73106-5224 | Oil Operator | Aug 2018 |
| 12404 | Halliburton Oil | | Oil & Gas Operator | Sep 2008 |
| 12405 | Halliburton Oil Producing Co. | Duncan, OK 73534 | Oil & Gas Operator | Apr 2016 |
| 12406 | Halliburton Operating Company | Plano, TX 75093 | Oil & Gas Operator | Nov 2025 |
| 12407 | Hallmark Oil And Gas Co., Inc. | | Oil & Gas Operator | Dec 2024 |
| 12408 | Hallmark Resources, Inc | Stilwell, OK 74960-0312 | Oil & Gas Operator | Sep 2020 |
| 12409 | Hallum Construction Inc | Seminole, OK 74868-2427 | Oil & Gas Operator | Sep 2014 |
| 12410 | Hallwell Gas & Oil Co. | | Oil & Gas Operator | Sep 1985 |
| 12411 | Hallwood Energy Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Feb 2005 |
| 12412 | Hallwood Petrole | | Oil & Gas Operator | Apr 1999 |
| 12413 | Hallwood Petroleum | Denver, CO 80237 | Oil & Gas Operator | Dec 1997 |
| 12414 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 12415 | Hallwood Petroleum, LLC | Dallas, TX 75219 | Oil & Gas Operator | Jan 2010 |
| 12416 | Halo Energy L.L.C. | Kilgore, TX 75662 | Oil Operator | Nov 2025 |
| 12417 | Halter Ralph P | Robertsville, OH 44670 | Oil Operator | Dec 1999 |
| 12418 | Halvey Energy Co. | Midland, TX 79702 | Oil & Gas Operator | Oct 2004 |
| 12419 | Halvey Energy, LLC | Midland, TX 79702 | Oil & Gas Operator | Nov 2025 |
| 12420 | Ham Oil & Gas, Inc. | Big Lake, TX 76932 | Oil & Gas Operator | Feb 2000 |
| 12421 | Ham Oil Company, LLC | | Oil Operator | Sep 2022 |
| 12422 | Hamblin Ralph Inc | MT Vernon, OH 43050 | Oil & Gas Operator | Dec 1991 |
| 12423 | Hamby Oil LLC | Ellinwood, KS 67526 | Oil Operator | May 2013 |
| 12424 | Hamil Oil & Gas LLC | Kingfisher, OK 73750-6500 | Oil & Gas Operator | Aug 2025 |
| 12425 | Hamill Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 1999 |
| 12426 | Hamill, Claud B. Estate Of | Houston, TX 77002 | Oil & Gas Operator | Nov 1995 |
| 12427 | Hamill, Flora Oil Co. | Levelland, TX 79336 | Oil & Gas Operator | Nov 2025 |
| 12428 | Hamilton B J | Ada, OK 74820-9404 | Oil & Gas Operator | Sep 1999 |
| 12429 | Hamilton Brother | | Gas Operator | May 1993 |
| 12430 | Hamilton Brothers | Plainview, TX 79073 | Oil & Gas Operator | Mar 2008 |
| 12431 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 12432 | Hamilton K M Oil & Gas Co | Ada, OK 74820 | Oil Operator | Jan 2013 |
| 12433 | Hamilton Leonard O | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 12434 | Hamilton, Clay | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Nov 2025 |
| 12435 | Hamilton, J. R. | Carrizo SPGS, TX 78834 | Oil & Gas Operator | Nov 2025 |
| 12436 | Hamilton, John M. | Wichita Falls, TX 76301 | Oil & Gas Operator | May 2001 |
| 12437 | Hamilton, W. B., Estate | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2004 |
| 12438 | Hamilton-Tedford Oper. Co., LLC | Wichita Falls, TX 76301 | Oil Operator | May 2007 |
| 12439 | Hamlin Oil Opera | | Oil Operator | May 1988 |
| 12440 | Hamm N R Contrac | | Oil & Gas Operator | Jun 1989 |
| 12441 | Hamm, Richard | Monahans, TX 79756 | Oil & Gas Operator | Mar 1994 |
| 12442 | Hamm, Richard Inc. | Monahans, TX 79756 | Oil & Gas Operator | Nov 2025 |
| 12443 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Nov 2025 |
| 12444 | Hamman, Blake | Graham, TX 76450 | Oil & Gas Operator | Jul 2020 |
| 12445 | Hammer Maclean Etal | Leon, KS 67074 | Oil Operator | Dec 2019 |
| 12446 | Hammer Oil Compa | | Oil Operator | Oct 1985 |
| 12447 | Hammer Oil Company | Post, TX 79356 | Oil & Gas Operator | Jun 2002 |
| 12448 | Hammer Oil Properties Inc | Enid, OK 73706-0144 | Oil & Gas Operator | Oct 2017 |
| 12449 | Hammer Ranch | Elmore City, OK 73433 | Oil & Gas Operator | Jan 2023 |
| 12450 | Hammerschmidt Wi | | Oil Operator | Sep 1991 |
| 12451 | Hammerschmidt, Leo | Plainville, KS 67663 | Oil Operator | Aug 2000 |
| 12452 | Hammerschmidt, William E | Plainville, KS 67663 | Oil Operator | Jun 2025 |
| 12453 | Hammersmith, Beverly | West Falls, NY 14170 | Gas Operator | Dec 2024 |
| 12454 | Hammon Properties | Wichita Falls, TX 76307 | Oil & Gas Operator | Apr 1996 |
| 12455 | Hammond Valley Colony, Inc. | Harlowton, MT 59036 | Gas Operator | Aug 2025 |
| 12456 | Hamon Jake L | Dallas, TX 75201-3902 | Oil & Gas Operator | Nov 1997 |
| 12457 | Hamon Oil Company | | Oil & Gas Operator | Aug 1985 |
| 12458 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 12459 | Hamp Oil | Ponca City, OK 74604 | Oil & Gas Operator | Sep 2002 |
| 12460 | Hamp Oil - Pace | | Oil & Gas Operator | Apr 1994 |
| 12461 | Hampton Corporation (The) | Norman, OK 73069-5910 | Oil Operator | Jun 2016 |
| 12462 | Hampton Oil & Gas | Early, TX 76802 | Gas Operator | Feb 2012 |
| 12463 | Hampton Resources Corporation | Houston, TX 77010 | Oil & Gas Operator | Mar 1996 |
| 12464 | Hampton, Jno. W. & Son | Wichita Falls, TX 76302 | Oil & Gas Operator | Nov 1998 |
| 12465 | Hanaco Operating | Holliday, TX 76366 | Oil Operator | Mar 2008 |
| 12466 | Hanaco, LLC | Holliday, TX 76366 | Oil Operator | Dec 2017 |
| 12467 | Hanagan Petroleum Corp | Roswell, NM 88201 | Oil & Gas Operator | Sep 1999 |
| 12468 | Hancock Leon | Kingston, OK 73439-9618 | Oil Operator | Dec 2014 |
| 12469 | Hancock, Burton W | Morrison, CO 80465 | Oil & Gas Operator | Dec 2017 |
| 12470 | Hand Oil Co. | Chanute, KS 66720 | Oil Operator | Nov 2000 |
| 12471 | Handy, Daniel G. | East Aurora, NY 14052 | Gas Operator | Dec 2024 |
| 12472 | Hane Operating, Inc. | Santa Anna, TX 76878 | Oil & Gas Operator | Sep 2005 |
| 12473 | Hanger Oil, L.L.C. | Wichita Falls, TX 76308 | Oil & Gas Operator | Nov 2025 |
| 12474 | Hank Oil & Gas, Inc. | Houston, TX 77056 | Oil & Gas Operator | Oct 2023 |
| 12475 | Hankamer, Curtis Corporation,The | Houston, TX 77024 | Oil & Gas Operator | Nov 2025 |
| 12476 | Hankey Oil Company | Houston, TX 77027 | Oil & Gas Operator | Feb 2010 |
| 12477 | Hankey Operating, Inc. | Houston, TX 77027 | Oil & Gas Operator | Mar 2016 |
| 12478 | Hanks, Christopher Glenn | Gainesville, TX 76240 | Oil & Gas Operator | Nov 2025 |
| 12479 | Hanley & Bird Inc | Tulsa, OK 74119 | Oil & Gas Operator | Dec 2011 |
| 12480 | Hanley Petroleum Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2017 |
| 12481 | Hanna M A Co | Cleveland, OH 44114-1824 | Oil & Gas Operator | Dec 1991 |
| 12482 | Hanna Oil And Gas Company | Fort Smith, AR 72901 | Oil & Gas Operator | Jul 2025 |
| 12483 | Hannathon Petroleum II, LLC | Midland, TX 79705 | Oil & Gas Operator | Nov 2025 |
| 12484 | Hannathon Petroleum, LLC | Midland, TX 79705 | Oil & Gas Operator | Nov 2025 |
| 12485 | Hannis Operating, LLC | Olney, TX 76374 | Oil & Gas Operator | Nov 2025 |
| 12486 | Hannold, Allan & Yolanda | Bloomfield, NY 14469 | Gas Operator | Dec 2024 |
| 12487 | Hanoco Inc | Tulsa, OK 74135 | Oil & Gas Operator | Jul 2025 |
| 12488 | Hanover Management Company | | Oil Operator | Aug 1979 |
| 12489 | Hanover Operating Company | Tulsa, OK 74101 | Oil & Gas Operator | Dec 1998 |
| 12490 | Hanselman, Michael D. | Jamestown, NY 14701 | Gas Operator | Dec 2024 |
| 12491 | Hansen Dane G TR | | Oil Operator | Feb 1995 |
| 12492 | Hansen Noel | Avant, OK 74001 | Oil Operator | Aug 2013 |
| 12493 | Hansen Oil Corporation | Shreveport, LA 71106 | Oil Operator | Apr 2003 |
| 12494 | Hansen, Dane G. - Trust | Logan, KS 67646 | Oil Operator | Oct 2013 |
| 12495 | Hanshu Production Company | Darrouzett, TX 79024 | Oil & Gas Operator | Apr 2017 |
| 12496 | Hanshu Production Company, LLC | Nashville, TN 37215 | Gas Operator | Nov 2025 |
| 12497 | Hanson Corporation | New Braunfels, TX 78132 | Oil & Gas Operator | Mar 2008 |
| 12498 | Hanson Energy | Glencoe, NM 88324 | Oil & Gas Operator | Jul 2008 |
| 12499 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 12500 | Hanson Natural Resources Co. | | Oil & Gas Operator | Nov 1991 |