| 1 | H & L Operators | | Oil & Gas Operator | Dec 2002 |
| 2 | H & O Oil Co. | | Oil & Gas Operator | Dec 1989 |
| 3 | H & R Oil Company | | Oil & Gas Operator | Dec 2000 |
| 4 | H. O. Strickler Operator | | Oil & Gas Operator | Dec 1993 |
| 5 | H. T. Hilliard & Co. | | Oil & Gas Operator | Dec 1999 |
| 6 | H. W. Reynolds Jr. | | Gas Operator | Dec 1984 |
| 7 | H.L. Hall & Sons LLC | | Oil & Gas Operator | Dec 2011 |
| 8 | H.T. Olsen Oil & Gas Operations | | Oil & Gas Operator | Apr 2025 |
| 9 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 10 | Harcor Energy Inc. | | Gas Operator | Dec 1999 |
| 11 | Harry Feder | | Oil & Gas Operator | Dec 1999 |
| 12 | Harter Energy Inc. | Tulsa, OK 74105 | Oil & Gas Operator | Mar 2025 |
| 13 | Hartley Natural Resource Development | | Oil & Gas Operator | Mar 2025 |
| 14 | Harvest Petroleum Inc. | Frisco, TX 75033 | Oil & Gas Operator | Jun 2025 |
| 15 | Hathaway Company | | Oil & Gas Operator | Mar 2025 |
| 16 | Hathaway LLC | | Oil & Gas Operator | Apr 2025 |
| 17 | Haussler Farms Inc. | | Oil Operator | Dec 1992 |
| 18 | Havens Oil Company | Early, TX 76803 | Oil & Gas Operator | Mar 2025 |
| 19 | HDT Inc. | | Oil & Gas Operator | Apr 2025 |
| 20 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 21 | Hellman Properties LLC | | Oil & Gas Operator | Apr 2025 |
| 22 | Henry And Jane Fong | | Oil Operator | Dec 1989 |
| 23 | Heritage Oil Company | Norman, OK 73070 | Oil & Gas Operator | Jul 2008 |
| 24 | Herley Olive Holdings LLC | | Oil & Gas Operator | Apr 2025 |
| 25 | Herley Petroleum | | Oil & Gas Operator | Dec 1997 |
| 26 | Herley-Kelley LLC | | Oil & Gas Operator | Apr 2025 |
| 27 | Herlindah Gallegos | | Oil Operator | Dec 2007 |
| 28 | Hershey Oil Corporation | Seminole, TX 79360 | Oil & Gas Operator | Jul 1992 |
| 29 | Hexadyne Energy Corp. | | Oil & Gas Operator | Dec 2013 |
| 30 | Hickory-National Co. | | Oil Operator | Dec 1986 |
| 31 | Hilliard Oil & Gas Inc | New Orleans, LA 70112 | Oil & Gas Operator | May 2001 |
| 32 | Hillside Oil Partners | | Oil & Gas Operator | Dec 1999 |
| 33 | Hiwa Petroleum Corp. | | Oil & Gas Operator | Mar 2025 |
| 34 | Hoag Memorial Hospital Presbyterian | | Gas Operator | Apr 2025 |
| 35 | Hoc Ca LLC | | Oil & Gas Operator | Apr 2025 |
| 36 | Holmes Western Oil Corporation | | Oil & Gas Operator | Apr 2025 |
| 37 | Horizon Operating Co. | | Oil & Gas Operator | Dec 1995 |
| 38 | Howard E. Caywood Inc. | | Oil & Gas Operator | Apr 2025 |
| 39 | Hoyt Energy L.L.C. | | Oil Operator | Apr 2025 |
| 40 | Hrubetz Oil Co. | Dallas, TX 75225 | Oil Operator | Sep 1986 |
| 41 | Hubl/Harbin | | Oil Operator | Dec 1994 |
| 42 | Hunt Enterprises | | Oil & Gas Operator | Mar 2025 |
| 43 | Hunter Edison Oil Development Limited Partnership | | Oil & Gas Operator | Apr 2025 |
| 44 | Huntington Beach Company | | Oil & Gas Operator | Dec 1998 |
| 45 | Huntington Beach Pacific Coast Enterprises LLC | | Oil & Gas Operator | Jan 2018 |
| 46 | Huntington Signal Oil Company | | Oil & Gas Operator | Dec 1997 |
| 47 | Husky Oil Company | Cody, WY 82414 | Oil & Gas Operator | Dec 1984 |
| 48 | Hvi Cat Canyon Inc. | | Oil & Gas Operator | Mar 2025 |