| 1 | H2ok LLC | Marble Falls, TX 78654 | Oil & Gas Operator | Jul 2025 |
| 2 | Hadson Petro USA Inc | | Oil & Gas Operator | Nov 2016 |
| 3 | Halcon Holdings Inc | Ada, OK 74820 | Oil & Gas Operator | Jun 2025 |
| 4 | Halcyon Natural Gas LLC | Oklahoma City, OK 73116-9111 | Oil & Gas Operator | Jun 2025 |
| 5 | Hall Edward L | Ada, OK 74820-3321 | Oil & Gas Operator | May 2025 |
| 6 | Hall Energy Company LLC | Oklahoma City, OK 73120-5020 | Oil & Gas Operator | Jul 2022 |
| 7 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 8 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 9 | Harding & Shelton Inc | Oklahoma City, OK 73104-2410 | Oil & Gas Operator | Jun 2025 |
| 10 | Harrell Petroleum Inc | Oklahoma City, OK 73102-7201 | Oil & Gas Operator | Oct 2017 |
| 11 | Harris Oil & Gas Company | Denver, CO 80202 | Oil & Gas Operator | Jun 2016 |
| 12 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 13 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 14 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Jun 2025 |
| 15 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 16 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Jul 2025 |
| 17 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Oct 2025 |
| 18 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 19 | HPC Incorporated | Denver, CO 80202 | Oil & Gas Operator | Nov 1998 |
| 20 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |