| 1 | H & L Operating Company | Amarillo, TX 79114 | Oil & Gas Operator | Feb 2020 |
| 2 | Hadson Petro USA Inc | | Oil & Gas Operator | Nov 2016 |
| 3 | Halcyon Natural Gas LLC | Oklahoma City, OK 73116-9111 | Oil & Gas Operator | Nov 2025 |
| 4 | Hall Exploration, Inc. | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2026 |
| 5 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 6 | Hamil Oil & Gas LLC | Kingfisher, OK 73750-6500 | Oil & Gas Operator | Feb 2026 |
| 7 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 8 | Hanna Oil And Gas Company | Fort Smith, AR 72901 | Oil & Gas Operator | Jan 2026 |
| 9 | Harding & Shelton Inc | Oklahoma City, OK 73104-2410 | Oil & Gas Operator | Jan 2026 |
| 10 | Hazlewood Oil & Gas Co Inc | Oklahoma City, OK 73139-9353 | Oil & Gas Operator | Apr 2022 |
| 11 | HCM | Dallas, TX 75206 | Oil & Gas Operator | Mar 2015 |
| 12 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 13 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Dec 2025 |
| 14 | Henderson Fred J | Okmulgee, OK 74447 | Oil & Gas Operator | Jan 2026 |
| 15 | Henry Petroleum Of Oklahoma LP | Midland, TX 79703-5000 | Oil & Gas Operator | Feb 2017 |
| 16 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 17 | Hester Jr J C | Lawton, OK 73502-1887 | Oil & Gas Operator | Oct 1997 |
| 18 | Highland Oil & Gas LLC | Houston, TX 77079-7220 | Oil & Gas Operator | Feb 2015 |
| 19 | Highline Operating, LLC | Oklahoma City, OK 73159 | Gas Operator | Jan 2026 |
| 20 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Feb 2026 |
| 21 | Holliday Exploration Inc | Oklahoma City, OK 73116 | Oil & Gas Operator | Nov 2005 |
| 22 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Apr 2026 |
| 23 | Home-Stake Royalty Corp., The | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2014 |
| 24 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 25 | HPC Incorporated | Denver, CO 80202 | Oil & Gas Operator | Nov 1998 |
| 26 | Hub-Hill Inc | San Antonio, TX 78230 | Oil Operator | Nov 1998 |
| 27 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Apr 2026 |
| 28 | Hunt Energy Corporation | | Oil & Gas Operator | Feb 2002 |
| 29 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Apr 2026 |
| 30 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Apr 2026 |
| 31 | Hyperion Energy LP | Dallas, TX 75206 | Oil & Gas Operator | May 2014 |