| 1 | H & H Star Energy Inc | Traverse City, MI 49684 | Oil & Gas Operator | Aug 2016 |
| 2 | H2ox Operating LLC | | Oil Operator | Feb 2024 |
| 3 | Ham Oil Company, LLC | | Oil Operator | Sep 2022 |
| 4 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 5 | Hanna Oil And Gas Company | Fort Smith, AR 72901 | Oil & Gas Operator | Feb 2024 |
| 6 | Hazlewood Oil & Gas Co Inc | Oklahoma City, OK 73139-9353 | Oil & Gas Operator | Apr 2022 |
| 7 | Heartlands Development Co Inc | Bristow, OK 74010-3826 | Oil & Gas Operator | May 2017 |
| 8 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Jan 2024 |
| 9 | Henry Petroleum Of Oklahoma LP | Midland, TX 79703-5000 | Oil & Gas Operator | Feb 2017 |
| 10 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 11 | High Sierra Crude Oil& Marketing LLC | Ardmore, OK 73401 | Oil Operator | Nov 2013 |
| 12 | Highland Energy Co | Dallas, TX 75201 | Oil & Gas Operator | Jun 1994 |
| 13 | Hiland Energy LP | Enid, OK 73701-0032 | Oil & Gas Operator | Dec 2022 |
| 14 | HK Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 15 | Hoover & Wilson Exp & Prod Inc | Fort Smith, AR 72913-5171 | Gas Operator | Jul 2013 |
| 16 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Jan 2024 |
| 17 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 18 | Hosco Operating Inc | Seminole, OK 74868-2447 | Oil & Gas Operator | Aug 2017 |
| 19 | Howard Energy Co Inc | Traverse City, MI 49684 | Oil & Gas Operator | Jun 2014 |
| 20 | Hsumy Oil & Gas Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2007 |
| 21 | Hy-Carb Energy Inc | | Oil & Gas Operator | Feb 2009 |