| 1 | D & S Operating | Texhoma, OK 73949 | Oil & Gas Operator | May 2001 |
| 2 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 3 | Darrah Oil Company, LLC | Wichita, KS 67201 | Oil & Gas Operator | Dec 2025 |
| 4 | Dart Oil Properties | Enid, OK 73703 | Oil & Gas Operator | Oct 1992 |
| 5 | Davis & Davis | | Oil & Gas Operator | Dec 2021 |
| 6 | Davis Bros. Oil Producers, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Apr 2020 |
| 7 | Dawson Resources Inc | Franktown, CO 80116 | Oil & Gas Operator | Mar 2015 |
| 8 | Dawson-Markwell Exploration Co. | Oklahoma City, OK 73101 | Oil & Gas Operator | Sep 2025 |
| 9 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 10 | Decalta International Corp | Denver, CO 80202 | Oil & Gas Operator | Mar 2015 |
| 11 | Denveramerican Petro LLC | | Oil & Gas Operator | May 2006 |
| 12 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 13 | Devon Energy Production Company, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 14 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 15 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Sep 2025 |
| 16 | Domar Oil & Gas Inc | Liberal, KS 67905 | Oil & Gas Operator | Oct 2000 |
| 17 | Dominion Ok TX E & P Inc | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2018 |
| 18 | Donson Corporation | Edmond, OK 73083-0341 | Oil & Gas Operator | Jul 1997 |
| 19 | Dorchester Hugoton LTD | Garland, TX 75042-8212 | Oil & Gas Operator | Mar 2004 |
| 20 | Dorchester Minerals Operating LP | Dallas, TX 75219 | Oil & Gas Operator | Jun 2022 |
| 21 | Dorchester Resources LP | Oklahoma City, OK 73154-8879 | Oil & Gas Operator | Aug 2021 |
| 22 | Drake Exploration Inc | Tulsa, OK 74105-4250 | Oil & Gas Operator | Sep 2025 |
| 23 | Duncan Oil Properties, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 24 | Dunne Equities Operating, Inc. | Houston, TX 77057 | Oil & Gas Operator | Aug 2022 |
| 25 | Dunne Equities, Inc. | Wichita, KS 67226 | Oil & Gas Operator | Apr 2014 |
| 26 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |