| 1 | H.L.Hawkins &H.L.Hawkins, Jr. | | Oil & Gas Operator | Feb 1989 |
| 2 | Hackberry Production, Inc. | | Oil Operator | Mar 1988 |
| 3 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 4 | Harbert Energy Corp | Irving, TX 75015-2510 | Oil & Gas Operator | Feb 1993 |
| 5 | HCW Exploration, Inc. | | Oil & Gas Operator | Jun 1986 |
| 6 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 7 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 8 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 9 | Helis Oil & Gas Company, L.L.C. | New Orleans, LA 70130 | Oil & Gas Operator | Oct 2023 |
| 10 | Hemus, Inc. | Bellaire, TX 77401 | Oil & Gas Operator | Sep 1994 |
| 11 | Henry Production Company, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Oct 2019 |
| 12 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Mar 2025 |
| 13 | Hilliard Petroleum Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Sep 2009 |
| 14 | Home Petroleum Corp | Victoria, TX 77902 | Oil & Gas Operator | Mar 2025 |
| 15 | Houston Exploration Co, The | Houston, TX 77002 | Oil & Gas Operator | Apr 2017 |
| 16 | Houston Oil & Gas Company, Inc. | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 17 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 18 | Huffco Petroleum Corporation | | Oil & Gas Operator | Jul 1988 |
| 19 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Mar 2025 |
| 20 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 21 | Hunter Oil & Gas, LLC | | Oil & Gas Operator | Oct 2001 |
| 22 | Hydrocarbon MGMT., Inc. | | Oil & Gas Operator | Mar 1997 |