| 1 | H & H Production Company | Muenster, TX 76252 | Oil & Gas Operator | Oct 2005 |
| 2 | H. L. Brown, Jr. | Midland, TX 79702 | Oil & Gas Operator | May 2001 |
| 3 | H.L.Hawkins &H.L.Hawkins, Jr. | | Oil & Gas Operator | Feb 1989 |
| 4 | Habetz Oilfield Saltwater Ser, Inc | | Oil Operator | Dec 2024 |
| 5 | Hallador Petroleum Company | | Oil & Gas Operator | Feb 1992 |
| 6 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 7 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 8 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Oct 2025 |
| 9 | Hardy Oil & Gas USA Inc. | Houston, TX 77079 | Oil & Gas Operator | Jun 1996 |
| 10 | Hassie Hunt Expl. Company | | Oil & Gas Operator | Aug 2008 |
| 11 | HCW Exploration, Inc. | | Oil & Gas Operator | Jun 1986 |
| 12 | Headington Energy Corporation | | Oil & Gas Operator | Aug 1992 |
| 13 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 14 | Headington Oil Company LLC | Dallas, TX 75204 | Oil & Gas Operator | Apr 2016 |
| 15 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 16 | Hebert & Rucks L.L.C. | | Oil & Gas Operator | May 2002 |
| 17 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Jun 2025 |
| 18 | Henderson Oil & Gas | | Oil Operator | Sep 1990 |
| 19 | Henry Production Company, Inc. | Lafayette, LA 70505 | Oil & Gas Operator | Oct 2019 |
| 20 | HGH Energy, Inc. | | Oil & Gas Operator | Jun 2001 |
| 21 | Hicks Production Co. | | Oil & Gas Operator | Apr 1991 |
| 22 | Highland Resources, Inc. | | Oil & Gas Operator | Dec 2004 |
| 23 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 24 | Hill Production | | Oil & Gas Operator | Nov 1981 |
| 25 | Hill Production Co Inc-Wisconsin | Humble, TX 77347 | Oil & Gas Operator | Jun 1993 |
| 26 | Hilliard Oil & Gas Inc | New Orleans, LA 70112 | Oil & Gas Operator | May 2001 |
| 27 | Hilliard Petroleum Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Sep 2009 |
| 28 | Holston-GR. Sou. Oil & Gas Co. | | Oil & Gas Operator | Mar 1981 |
| 29 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 30 | Howard'S Well Service | | Oil Operator | Jul 2007 |
| 31 | Huffco Petroleum Corporation | | Oil & Gas Operator | Jul 1988 |
| 32 | Hugh A. Hawthorne, Et Al | | Oil & Gas Operator | Dec 1978 |
| 33 | Hughes & Hughes | | Oil & Gas Operator | May 1984 |
| 34 | Hughes Denny Offshore Expl Inc | | Oil & Gas Operator | Nov 1988 |
| 35 | Hughes Eastern Petroleum, Inc. | | Oil & Gas Operator | Apr 1993 |
| 36 | Hughes Eastern Petroleum, LTD. | | Oil & Gas Operator | Jun 1986 |
| 37 | Hughes-Denny Petroleum Co.,Inc | | Oil & Gas Operator | Dec 1987 |
| 38 | Hughes-Leckelt-Maybrier PRDCRS | | Oil Operator | Mar 2022 |
| 39 | Hunt Investment Corporation | | Oil & Gas Operator | Jun 1989 |
| 40 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 41 | Hy-Mark Oil & Gas, Inc. | | Oil Operator | Mar 1991 |
| 42 | Hydrocarbon MGMT., Inc. | | Oil & Gas Operator | Mar 1997 |