| 1 | Hadson Energy Resources Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1994 |
| 2 | Hadson Petroleum (USA), Inc. | | Oil & Gas Operator | Dec 1992 |
| 3 | Hassie Hunt Expl. Company | | Oil & Gas Operator | Aug 2008 |
| 4 | HCW Exploration, Inc. | | Oil & Gas Operator | Jun 1986 |
| 5 | Helis Oil & Gas Company, L.L.C. | New Orleans, LA 70130 | Oil & Gas Operator | Oct 2023 |
| 6 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Jun 2025 |
| 7 | Henry Production Company, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Oct 2019 |
| 8 | Hicks Production Co. | | Oil & Gas Operator | Apr 1991 |
| 9 | High-Hope Oil And Gas, Inc | | Oil & Gas Operator | Mar 2017 |
| 10 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 11 | Hilliard Petroleum Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Sep 2009 |
| 12 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Oct 2025 |
| 13 | Houma Salt Water Disposal Corp | | Oil Operator | Dec 2020 |
| 14 | Houston Energy, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 15 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 16 | Howell Petroleum Corporation | Houston, TX 77251 | Oil & Gas Operator | Oct 2015 |
| 17 | HS Resources, Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2005 |
| 18 | Huffco Petroleum Corporation | | Oil & Gas Operator | Jul 1988 |
| 19 | Hughes Denny Offshore Expl Inc | | Oil & Gas Operator | Nov 1988 |
| 20 | Hughes Eastern Petroleum, Inc. | | Oil & Gas Operator | Apr 1993 |
| 21 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 22 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 23 | Hunt Petroleum Corporation | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 24 | Hydrocarbon MGMT., Inc. | | Oil & Gas Operator | Mar 1997 |