| 1 | H-M Resource Management, Inc. | Houston, TX 77055 | Oil & Gas Operator | Feb 2023 |
| 2 | Halex Oil Corporation | Houston, TX 77057 | Oil & Gas Operator | Oct 2025 |
| 3 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 4 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Oct 2025 |
| 5 | Hankey Oil Company | Houston, TX 77027 | Oil & Gas Operator | Feb 2010 |
| 6 | Hanson Minerals Co. | Houston, TX 77042 | Oil & Gas Operator | Oct 1993 |
| 7 | Hanson Production Company | Cuero, TX 77954 | Oil & Gas Operator | Jul 2009 |
| 8 | Hardwick Oil Company | Sugar Land, TX 77478 | Oil & Gas Operator | Nov 2014 |
| 9 | Harrison Interests, LTD. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 10 | Harrison, Dan J III&Bruce F Est | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 11 | Harrison, Dan J. III&Bruce F. | Houston, TX 77002 | Oil & Gas Operator | Mar 2008 |
| 12 | Hart Petroleum Services, Inc | Corpus Chrsti, TX 78410 | Oil & Gas Operator | Jul 2025 |
| 13 | High Plains Gas Systems, Inc. | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 14 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 15 | Hilty Interests, Inc. | Kerrville, TX 78028 | Oil & Gas Operator | Jun 1989 |
| 16 | Horizon Exploration Company | Houston, TX 77019 | Oil & Gas Operator | Aug 2002 |
| 17 | Horizon Prod. And Operating, LLC | Houston, TX 77019 | Oil & Gas Operator | Oct 2025 |
| 18 | Hou-Tex, Inc. | Houston, TX 77224 | Oil & Gas Operator | Jun 2001 |
| 19 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 20 | Houston Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 21 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 22 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2005 |
| 23 | Hurd Enterprises, LTD. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 2025 |
| 24 | Hurricane Oil And Gas Co., Inc. | Houston, TX 77057 | Oil & Gas Operator | Mar 2008 |