| 1 | D & D Pipe & Equipment Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Mar 2005 |
| 2 | D & J Oil Company | Kermit, TX 79745 | Oil & Gas Operator | Oct 2025 |
| 3 | D C Energy, Inc. | Oklahoma City, OK 73134 | Oil & Gas Operator | Apr 2020 |
| 4 | D-Mil Production Inc | Argyle, TX 76226 | Oil & Gas Operator | Oct 2025 |
| 5 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 6 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 7 | Daube Company The | Ardmore, OK 73401 | Oil & Gas Operator | Jul 2025 |
| 8 | Dawson Resources Inc | Franktown, CO 80116 | Oil & Gas Operator | Mar 2015 |
| 9 | Dawson-Markwell Exploration Co. | Oklahoma City, OK 73101 | Oil & Gas Operator | Jun 2025 |
| 10 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 11 | Decalta International Corp | Denver, CO 80202 | Oil & Gas Operator | Mar 2015 |
| 12 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 13 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 14 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 15 | Diamond Energy Operating Company | Tulsa, OK 74137 | Oil & Gas Operator | Mar 2005 |
| 16 | Dinero Operating Co | Midland, TX 79702 | Oil & Gas Operator | Oct 2025 |
| 17 | Dinsmore C E | Enid, OK 73702 | Oil & Gas Operator | May 2009 |
| 18 | DLB Energy Corporation | Oklahoma City, OK 73118-1401 | Oil & Gas Operator | Dec 2014 |
| 19 | DLB Oil & Gas, Inc. | Big Lake, TX 76932 | Oil & Gas Operator | Oct 2025 |
| 20 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | Aug 2025 |
| 21 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 22 | Dominion Ok TX E & P Inc | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2018 |
| 23 | Dorchester Resources LP | Oklahoma City, OK 73154-8879 | Oil & Gas Operator | Aug 2021 |
| 24 | Draco Production Company | Tulsa, OK 74133 | Oil & Gas Operator | Jul 2012 |
| 25 | Dragon Energy LLC | Tulsa, OK 74135-7234 | Oil & Gas Operator | Feb 2015 |
| 26 | Draw Oil & Gas Inc | | Oil & Gas Operator | Jun 1995 |
| 27 | Duggins Equipment Inc | Woodward, OK 73802-1213 | Gas Operator | Jun 2025 |
| 28 | Duncan Oil Properties, Inc. | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 29 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |