| 1 | H & L Operating Company | Amarillo, TX 79114 | Oil & Gas Operator | Feb 2020 |
| 2 | H E C H Corporation | Ada, OK 74820-9528 | Oil Operator | Sep 2019 |
| 3 | Hall Resources Corporation | Independence, MO 64057-2158 | Oil & Gas Operator | Jun 2016 |
| 4 | Hallmark Resources, Inc | Stilwell, OK 74960-0312 | Oil & Gas Operator | Sep 2020 |
| 5 | Hamilton B J | Ada, OK 74820-9404 | Oil & Gas Operator | Sep 1999 |
| 6 | Hamilton K M Oil & Gas Co | Ada, OK 74820 | Oil Operator | Jan 2013 |
| 7 | Hamilton Properties & Investments L.L.C. | Ada, OK 74820 | Oil Operator | Dec 2024 |
| 8 | Harrod Leasing | Edmond, OK 73034 | Oil & Gas Operator | Dec 2024 |
| 9 | Hazelwood Louis J | Albuquerque, NM 87111-6870 | Oil & Gas Operator | Feb 2023 |
| 10 | HCG Energy Corporation & Subs | | Oil & Gas Operator | Mar 2015 |
| 11 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 12 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 13 | Heaton Everill L | Exeter, CA 93221-2340 | Oil & Gas Operator | Sep 2014 |
| 14 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 15 | Highmark Energy Operating, LLC | Poynor, TX 75782 | Oil & Gas Operator | Mar 2025 |
| 16 | HRC Production Co | Houston, TX 77002 | Oil & Gas Operator | Nov 2024 |
| 17 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Mar 2025 |
| 18 | Hughes George B | Asher, OK 74826-0165 | Oil & Gas Operator | Mar 2011 |