| 1 | O & O Operators, LLC. | Fate, TX 75132 | Oil & Gas Operator | Feb 2026 |
| 2 | O'Brien, George H. Jr. | Midland, TX 79701 | Oil & Gas Operator | Jun 1994 |
| 3 | O'Ryan Oil And Gas | Odessa, TX 79768 | Oil & Gas Operator | Feb 2026 |
| 4 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Feb 2026 |
| 5 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 6 | Occidental Energy Marketing, Inc. | Houston, TX 77227 | Gas Operator | Sep 2015 |
| 7 | Occidental Permian LTD. | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 8 | Ocean Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 9 | Octane Energy Operating, LLC | Midland, TX 79701 | Oil & Gas Operator | Feb 2026 |
| 10 | Odessa Exploration, Inc. | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 11 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 12 | Ogris Operating, LLC | Midland, TX 79710 | Oil & Gas Operator | Feb 2026 |
| 13 | Oilfield Management, Inc. (A) | Midland, TX 79702 | Oil & Gas Operator | Feb 2026 |
| 14 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Feb 2026 |
| 15 | Ojai Oil Company | Camarillo, CA 93012 | Oil & Gas Operator | Nov 2025 |
| 16 | Ok Arena Operating Company | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2026 |
| 17 | Okla. Magic Circle Energy Corp. | Shawnee, OK 74801 | Oil & Gas Operator | Jul 2004 |
| 18 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 19 | Olsen Energy Inc. | Boerne, TX 78006 | Oil & Gas Operator | Feb 2026 |
| 20 | Omar Operating Company | Midland, TX 79702 | Oil & Gas Operator | Sep 2013 |
| 21 | Opal Resources Operating Co.,LLC | Cypress, TX 77429 | Oil & Gas Operator | Jan 2019 |
| 22 | Opco Oil & Gas Co. | Dallas, TX 75231 | Oil & Gas Operator | Aug 2003 |
| 23 | Orbitron Operating Corp. | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1995 |
| 24 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 25 | Oso Exploration & Production, LLC | Houston, TX 77269 | Oil Operator | Feb 2026 |
| 26 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 27 | Ouut Investing LLC | Mineral Wells, TX 76068 | Oil Operator | Mar 2020 |
| 28 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Feb 2026 |
| 29 | Owens Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Aug 1995 |
| 30 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |
| 31 | Oxy USA WTP LP | Houston, TX 77046 | Oil & Gas Operator | Feb 2026 |