| 1 | H & L Operating Co., L.L.P. | Amarillo, TX 79114 | Oil & Gas Operator | Aug 2022 |
| 2 | H & L Operating Company | Amarillo, TX 79114 | Oil & Gas Operator | Feb 2020 |
| 3 | H & W Operating | Woodward, OK 73802 | Oil & Gas Operator | Apr 2000 |
| 4 | H A Oil & Gas Company | Laverne, OK 73848-0100 | Gas Operator | Mar 2002 |
| 5 | Hadson Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 6 | Halcon Holdings Inc | Ada, OK 74820 | Oil & Gas Operator | Oct 2025 |
| 7 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 8 | Harbor Resources LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Feb 2026 |
| 9 | Harding & Shelton Inc | Oklahoma City, OK 73104-2410 | Oil & Gas Operator | Nov 2025 |
| 10 | Harding And Shelton Exploration LLC | Oklahoma City, OK 73101-1557 | Oil & Gas Operator | Nov 2025 |
| 11 | Harken Exploration Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2008 |
| 12 | Harrell Petroleum Inc | Oklahoma City, OK 73102-7201 | Oil & Gas Operator | Oct 2017 |
| 13 | Hartman Oil Company Inc | Wichita, KS 67206 | Oil & Gas Operator | Sep 2025 |
| 14 | Hawkins Oil & Gas Inc | Tulsa, OK 74103 | Oil & Gas Operator | Dec 2016 |
| 15 | Hazlewood Oil & Gas Co Inc | Oklahoma City, OK 73139-9353 | Oil & Gas Operator | Apr 2022 |
| 16 | HCM | Dallas, TX 75206 | Oil & Gas Operator | Mar 2015 |
| 17 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 18 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 19 | Heartland Environmental Services | Watonga, OK 73080 | Oil & Gas Operator | May 1999 |
| 20 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Nov 2025 |
| 21 | Hennessey Oil & Gas LLC | Hennessey, OK 73742-0212 | Oil & Gas Operator | Sep 2024 |
| 22 | Heritage Petroleum, Inc. | Stillwater, OK 74076 | Oil & Gas Operator | Feb 2026 |
| 23 | Herrman & Ikenberry | Cushing, OK 74023-0247 | Oil & Gas Operator | Dec 2003 |
| 24 | Hinkle Engineering, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2016 |
| 25 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Dec 2025 |
| 26 | Holke Dave Consulting Inc | Meridian, ID 83646-4812 | Oil & Gas Operator | Nov 2025 |
| 27 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 28 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 29 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 30 | Hosco Operating Inc | Seminole, OK 74868-2447 | Oil & Gas Operator | Aug 2017 |
| 31 | Hovas Enterprises | Perkins, OK 74059 | Oil & Gas Operator | Mar 2014 |
| 32 | HRB Operating Company, Inc. | Bridgeport, TX 76426 | Oil & Gas Operator | Feb 2026 |
| 33 | Huber J M Corp | Edison, NJ 08837 | Oil & Gas Operator | Feb 2026 |
| 34 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 35 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |