| 1 | H & L Operating Company | Amarillo, TX 79114 | Oil & Gas Operator | Feb 2020 |
| 2 | Hadson Petro USA Inc | | Oil & Gas Operator | Nov 2016 |
| 3 | Hadson Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 4 | Hall Energy Company LLC | Oklahoma City, OK 73120-5020 | Oil & Gas Operator | Jul 2022 |
| 5 | Hall Resources Corporation | Independence, MO 64057-2158 | Oil & Gas Operator | Jun 2016 |
| 6 | Hallwood Petroleum, Inc. | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 7 | Hamil Oil & Gas LLC | Kingfisher, OK 73750-6500 | Oil & Gas Operator | Aug 2025 |
| 8 | Hamilton Brothers Oil Co. | Houston, TX 77057 | Oil & Gas Operator | Mar 2015 |
| 9 | Harbor Resources LLC | Oklahoma City, OK 73120 | Oil & Gas Operator | Dec 2025 |
| 10 | Harding & Shelton Inc | Oklahoma City, OK 73104-2410 | Oil & Gas Operator | Aug 2025 |
| 11 | Harding And Shelton Exploration LLC | Oklahoma City, OK 73101-1557 | Oil & Gas Operator | Aug 2025 |
| 12 | Haydens Oil And Gas LLC | Dover, OK 73734 | Oil & Gas Operator | Aug 2025 |
| 13 | Hays Production LLC | Velma, OK 73491 | Oil & Gas Operator | Aug 2025 |
| 14 | Hazlewood Oil & Gas Co Inc | Oklahoma City, OK 73139-9353 | Oil & Gas Operator | Apr 2022 |
| 15 | Headington Oil Company | Dallas, TX 75231 | Oil & Gas Operator | Dec 2016 |
| 16 | Helmerich & Payne, Inc. | Tulsa, OK 74114 | Oil & Gas Operator | Aug 2025 |
| 17 | Henderson Fred J | Okmulgee, OK 74447 | Oil & Gas Operator | Aug 2025 |
| 18 | Hep Oil Company, LTD. | Gainesville, TX 76240 | Oil & Gas Operator | Mar 2012 |
| 19 | Hep Oil GP, LLC | Gainesville, TX 76241 | Oil & Gas Operator | Mar 2015 |
| 20 | Hess Corporation | Houston, TX 77010 | Oil & Gas Operator | Aug 2017 |
| 21 | Hiawatha Exploration Company | Oklahoma City, OK 73116-7326 | Oil & Gas Operator | Mar 2009 |
| 22 | High Sierra Water Services Mid Continent LLC | Denver, CO 80209 | Oil Operator | Feb 2010 |
| 23 | Highland Minerals Inc | Tulsa, OK 74145-7627 | Oil & Gas Operator | Apr 2015 |
| 24 | Highland Oil & Gas LLC | Houston, TX 77079-7220 | Oil & Gas Operator | Feb 2015 |
| 25 | Hinkle Engineering, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2016 |
| 26 | Hinkle Oil And Gas Inc | Oklahoma City, OK 73112-4275 | Oil & Gas Operator | Sep 2025 |
| 27 | HK Energy Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2023 |
| 28 | Hodgden Operating Co., Inc. | Enid, OK 73702 | Oil & Gas Operator | Sep 2025 |
| 29 | Holke Dave Consulting Inc | Meridian, ID 83646-4812 | Oil & Gas Operator | Aug 2025 |
| 30 | Home-Stake Royalty Corp., The | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2014 |
| 31 | Hondo Oil & Gas Company | Roswell, NM 88202 | Oil & Gas Operator | Aug 2006 |
| 32 | Horizon Natural Gas Company | Tulsa, OK 74170 | Oil & Gas Operator | Oct 2024 |
| 33 | Horizon Natural Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2019 |
| 34 | Hugoton Energy Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Dec 2019 |
| 35 | Hunt Engineering Inc | Norman, OK 73069-4093 | Oil & Gas Operator | Feb 2019 |
| 36 | Hunt Oil Company | Dallas, TX 75201 | Oil & Gas Operator | Dec 2025 |
| 37 | Huntington Energy LLC | Nichols Hill, OK 73116 | Oil & Gas Operator | Dec 2025 |
| 38 | Hunton Oil & Gas Corporation | Oklahoma City, OK 73154-0191 | Oil & Gas Operator | May 2019 |
| 39 | Hux Oil Company LLC | Kingfisher, OK 73750 | Oil & Gas Operator | Aug 2025 |