| 1 | Oasis Operating, Inc. | Lubbock, TX 79404 | Oil & Gas Operator | Nov 2020 |
| 2 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 3 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Oct 2025 |
| 4 | Okie Operating Company, LTD. | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 5 | Oklahoma Marlin Oil Corporation | Oklahoma City, OK 73113 | Oil & Gas Operator | Feb 2020 |
| 6 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 7 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | Oct 2025 |
| 8 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Oct 2025 |
| 9 | Oringderff, Alma Oil Properties | Dallas, TX 75225 | Oil & Gas Operator | Mar 2012 |
| 10 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 11 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 12 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Oct 2025 |
| 13 | Ozark Exploration, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Oct 2025 |