| 1 | Dar-Lon Operating Company | Lamont, OK 74643 | Oil & Gas Operator | Oct 2000 |
| 2 | Darco Petroleum, Inc. | Bartlesville, OK 74005 | Oil & Gas Operator | Dec 2020 |
| 3 | Darling Dan Oil | | Oil & Gas Operator | Sep 2018 |
| 4 | Darling Oil Corporation | Lamont, OK 74643 | Oil & Gas Operator | Feb 2025 |
| 5 | David E Morgan Inc | Danville, CA 94506-2035 | Oil & Gas Operator | Feb 2025 |
| 6 | Davis Bros. Oil Producers, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2020 |
| 7 | Davis, Joe D. | Fort Smith, AR 72903 | Gas Operator | Mar 2015 |
| 8 | Dawson-Markwell Exploration Co. | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2025 |
| 9 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | Feb 2025 |
| 10 | Delong Oil & Gas Services, Inc. | Cushing, OK 74023 | Oil & Gas Operator | Dec 2024 |
| 11 | Demco Oil & Gas Company | Blackwell, OK 74631-4203 | Oil & Gas Operator | Feb 2025 |
| 12 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2025 |
| 13 | Devon Resources Corporation | Jenks, OK 74037-3525 | Oil & Gas Operator | Feb 2025 |
| 14 | Diamond Cross Oil Co LLC | Ponca City, OK 74601-1104 | Oil & Gas Operator | Feb 2025 |
| 15 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Jun 2025 |
| 16 | DMS Investments Inc | Tulsa, OK 74132-2690 | Oil & Gas Operator | Mar 2015 |
| 17 | Dominion Ok TX E & P Inc | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2018 |
| 18 | Donray Petroleum LLC | Choctaw, OK 73020 | Oil & Gas Operator | Feb 2025 |
| 19 | Drake Exploration LLC | Arkansas City, KS 67005 | Oil & Gas Operator | Feb 2025 |
| 20 | Dundee Oil & Supply Inc | Tulsa, OK 74101 | Oil & Gas Operator | Apr 2001 |
| 21 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |
| 22 | Dyno Energy LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Mar 2025 |