| 1 | H & S Drilling Co Inc | Frazeysburg, OH 43822-0040 | Oil & Gas Operator | Dec 2016 |
| 2 | Halcon Operating Co., Inc. | Houston, TX 77024 | Oil & Gas Operator | Mar 2025 |
| 3 | Hall Energy Company LLC | Oklahoma City, OK 73120-5020 | Oil & Gas Operator | Jul 2022 |
| 4 | Hamill Resources, Inc. | Houston, TX 77002 | Oil & Gas Operator | Apr 1999 |
| 5 | Hamill, Claud B. Estate Of | Houston, TX 77002 | Oil & Gas Operator | Nov 1995 |
| 6 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Mar 2025 |
| 7 | Hampton Resources Corporation | Houston, TX 77010 | Oil & Gas Operator | Mar 1996 |
| 8 | Hansen Oil Corporation | Shreveport, LA 71106 | Oil Operator | Apr 2003 |
| 9 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 10 | Harman Operating Company, Inc. | Tyler, TX 75702 | Oil & Gas Operator | Dec 2007 |
| 11 | Hawkwood Energy Operating, LLC | Houston, TX 77224 | Oil & Gas Operator | Apr 2022 |
| 12 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Nov 2024 |
| 13 | Hicon Gas Producers, Inc. | New York, NY 10110 | Oil & Gas Operator | Oct 1999 |
| 14 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Mar 2025 |
| 15 | Hopkins, T. M. Operating Co. | Kilgore, TX 75663 | Oil & Gas Operator | Mar 2025 |
| 16 | Hughey, Gaylord T. SR. Oper. Co. | Tyler, TX 75711 | Oil & Gas Operator | Feb 1998 |
| 17 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Mar 2025 |
| 18 | Hunt Petroleum Corporation | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 19 | Huntington Resources Inc | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2006 |
| 20 | Hydrogeo, L.L.C. | Houston, TX 77074 | Oil & Gas Operator | Mar 2025 |