| 1 | H.L.Hawkins &H.L.Hawkins, Jr. | | Oil & Gas Operator | Feb 1989 |
| 2 | Hadson Energy Resources Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1994 |
| 3 | Hadson Petroleum (USA), Inc. | | Oil & Gas Operator | Dec 1992 |
| 4 | Hamon Oil Company | | Oil & Gas Operator | Aug 1985 |
| 5 | Hamon Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2011 |
| 6 | Hardey Co., The | Shreveport, LA 71107 | Oil & Gas Operator | Oct 2025 |
| 7 | Hawthorne Oil And Gas Corp. | Houston, TX 77227 | Oil & Gas Operator | Sep 1993 |
| 8 | Hawthorne-Tipco | | Oil & Gas Operator | Oct 1978 |
| 9 | Helis Oil & Gas Company, L.L.C. | New Orleans, LA 70130 | Oil & Gas Operator | Oct 2023 |
| 10 | Henry Production Company, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Oct 2019 |
| 11 | HGH Energy, Inc. | | Oil & Gas Operator | Jun 2001 |
| 12 | Highland Resources, Inc. | | Oil & Gas Operator | Dec 2004 |
| 13 | Highlander Oil & Gas Assets LLC | | Gas Operator | Jan 2025 |
| 14 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 15 | HK Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 16 | Holden Energy Corporation | Ardmore, OK 73401 | Oil & Gas Operator | Mar 2015 |
| 17 | Houston Energy Operating, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jul 2020 |
| 18 | Hughes Denny Offshore Expl Inc | | Oil & Gas Operator | Nov 1988 |
| 19 | Hughes Eastern Petroleum, Inc. | | Oil & Gas Operator | Apr 1993 |
| 20 | Hughes-Denny Petroleum Co.,Inc | | Oil & Gas Operator | Dec 1987 |
| 21 | Hughes-Nicklaus Oil Co., LTD. | | Oil & Gas Operator | Feb 1986 |
| 22 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 23 | Hydrocarbon MGMT., Inc. | | Oil & Gas Operator | Mar 1997 |