| 1 | Hadaway Consulting And Engineering LLC | Canadian, TX 79014 | Oil & Gas Operator | Jul 2025 |
| 2 | Hallco Petroleum Inc | Oklahoma City, OK 73106-5224 | Oil Operator | Aug 2018 |
| 3 | Halliburton Oil Producing Co. | Duncan, OK 73534 | Oil & Gas Operator | Apr 2016 |
| 4 | Hamon Jake L | Dallas, TX 75201-3902 | Oil & Gas Operator | Nov 1997 |
| 5 | Hamp Oil | Ponca City, OK 74604 | Oil & Gas Operator | Sep 2002 |
| 6 | Har-Ken Oil Co | | Oil & Gas Operator | Dec 2021 |
| 7 | Hargraves Elston | Ponca City, OK 74604 | Oil & Gas Operator | Jul 2003 |
| 8 | Hazelwood Prod & Exp Co LLC | Oklahoma City, OK 73116-9037 | Oil & Gas Operator | Jun 2025 |
| 9 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 10 | Heath Oil Co., Inc. | Washington, OK 73093-4702 | Oil & Gas Operator | Jun 2025 |
| 11 | Hewitt Energy Group, Inc. | Salt Lake City, UT 84111 | Oil & Gas Operator | Apr 2015 |
| 12 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Jul 2025 |
| 13 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 14 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 15 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 16 | Houseco Petroleum Inc | Bristow, OK 74010-0842 | Oil & Gas Operator | Aug 2002 |
| 17 | Howco Oil And Gas | Stroud, OK 74079-9604 | Oil & Gas Operator | Mar 2015 |
| 18 | Howell C W | Wichita Falls, TX 76308 | Oil & Gas Operator | Apr 2015 |
| 19 | Hyperion Energy LP | Dallas, TX 75206 | Oil & Gas Operator | May 2014 |