| 1 | H & O Operating Co | Odessa, TX 79764 | Oil & Gas Operator | Mar 2008 |
| 2 | H&G Petroleum Corporation | Midland, TX 79710 | Oil & Gas Operator | Oct 2025 |
| 3 | Hadson Energy Resources Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 1994 |
| 4 | Hallwood Energy Corporation | Oklahoma City, OK 73154 | Oil & Gas Operator | Feb 2005 |
| 5 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 6 | Halvey Energy, LLC | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 7 | Hamman Oil & Refining Company | Houston, TX 77098 | Oil & Gas Operator | Oct 2025 |
| 8 | Hannathon Petroleum, LLC | Midland, TX 79705 | Oil & Gas Operator | Oct 2025 |
| 9 | Hanson Corporation | New Braunfels, TX 78132 | Oil & Gas Operator | Mar 2008 |
| 10 | Harrison Interests, LTD. | Houston, TX 77002 | Oil & Gas Operator | Oct 2025 |
| 11 | Hat Oil & Gas, Inc. | Slaton, TX 79364 | Oil & Gas Operator | Feb 2002 |
| 12 | HCM | Dallas, TX 75206 | Oil & Gas Operator | Mar 2015 |
| 13 | Hec Petroleum, Inc | Midland, TX 79705 | Oil & Gas Operator | Mar 2006 |
| 14 | Henderson & Erickson, Inc. | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 15 | Hendrix, John H. Corporation | Midland, TX 79705 | Oil & Gas Operator | Sep 2018 |
| 16 | Henry Petroleum Corp. | Midland, TX 79703 | Oil & Gas Operator | Mar 2001 |
| 17 | Henry Petroleum LP | Midland, TX 79701 | Oil & Gas Operator | Dec 2008 |
| 18 | Henry Resources LLC | Midland, TX 79703 | Oil & Gas Operator | Oct 2025 |
| 19 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 20 | Hess Seminole Assets LLC | Seminole, TX 79360 | Oil & Gas Operator | Aug 2017 |
| 21 | Hexp Operating, LLC | Midland, TX 79705 | Oil & Gas Operator | Oct 2025 |
| 22 | Hi - Mountain Energy Corporation | Odessa, TX 79762 | Oil & Gas Operator | Oct 2025 |
| 23 | Hicon Gas Producers, Inc. | New York, NY 10110 | Oil & Gas Operator | Oct 1999 |
| 24 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Oct 2025 |
| 25 | Hillin Prod. Co. | Odessa, TX 79760 | Oil & Gas Operator | Apr 2002 |
| 26 | Hillin Simon/Prime Expl., L.C. | Midland, TX 79702 | Oil & Gas Operator | Jun 2000 |
| 27 | Hillin-Simon Oil Company | Houston, TX 77079 | Oil & Gas Operator | Mar 2013 |
| 28 | HK Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 29 | Home-Stake Oil & Gas Company | Plano, TX 75093 | Oil & Gas Operator | Jul 2025 |
| 30 | Home-Stake Royalty Corp., The | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2014 |
| 31 | Hopkins, T. M. Operating Co. | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 32 | Horizon Oil & Gas Co. | Dallas, TX 75221 | Oil & Gas Operator | Jan 2005 |
| 33 | Houghton Oil & Gas, Inc. | Midland, TX 79701 | Oil & Gas Operator | Mar 2009 |
| 34 | Houston Energy Operating, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jul 2020 |
| 35 | Houston Energy, L.P. | Houston, TX 77002 | Oil & Gas Operator | Jan 2014 |
| 36 | Houston Oil & Minerals Corp. | Houston, TX 77002 | Oil & Gas Operator | Aug 1996 |
| 37 | Hub-Cap Oil Company | Arlington, TX 76016 | Oil & Gas Operator | Dec 2013 |
| 38 | Hubcap Oil, LLC | Boerne, TX 78015 | Oil Operator | Oct 2025 |
| 39 | Hughes, Dan A. Company, L.P. | Beeville, TX 78104 | Oil & Gas Operator | Oct 2025 |
| 40 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 41 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 42 | Hunt Petroleum (Aec), Inc. | Dallas, TX 75201 | Oil & Gas Operator | Nov 2008 |
| 43 | HW Operating, LLC | Wichita Falls, TX 76308 | Oil & Gas Operator | Oct 2025 |