| 1 | D & D Oil Company | Dayton, TX 77535 | Oil & Gas Operator | Dec 2025 |
| 2 | D & J Oil Company | Kermit, TX 79745 | Oil & Gas Operator | Dec 2025 |
| 3 | D J Simmons, Inc | Farmington, NM 87499 | Oil & Gas Operator | Apr 2020 |
| 4 | Dalen Resources Oil & Gas | Dallas, TX 75206-3922 | Oil & Gas Operator | Jan 1996 |
| 5 | Daniels Petroleum Co | Denver, CO 80202 | Oil & Gas Operator | Mar 2003 |
| 6 | Davis Oil Company | Denver, CO 80202 | Oil & Gas Operator | Jun 1988 |
| 7 | De Kalb Agric Assn Inc | Vernal, UT | Oil & Gas Operator | Jun 1965 |
| 8 | Del-Rio Resources Inc | Vernal, UT 84079 | Oil & Gas Operator | Jan 2018 |
| 9 | Delhi-Taylor Oil Corp | | Oil & Gas Operator | Dec 1974 |
| 10 | Delhi-Trading LLC | Durango, CO 81301 | Oil & Gas Operator | Oct 2025 |
| 11 | Delta Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2024 |
| 12 | Devon Energy Operating Corp | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2013 |
| 13 | Devon Energy Production Company, L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2025 |
| 14 | Diamond Shamrock Corp | Amarillo, TX 79105 | Oil & Gas Operator | Jan 1987 |
| 15 | Diamond Shamrock Expl | Dallas, TX 75201 | Oil & Gas Operator | May 1987 |
| 16 | Dirty Devil LP | Eenglewood, CO 80111 | Oil & Gas Operator | Apr 1989 |
| 17 | Discovery Natural Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 18 | Diversified Energy LLC | Parker, CO 80138 | Oil & Gas Operator | Aug 2025 |
| 19 | DKM Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2011 |
| 20 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 21 | Dominion Ok TX E & P Inc | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2018 |
| 22 | Dougherty, H W | Petaluma, CA 94954 | Gas Operator | Oct 2019 |
| 23 | Dugan Production Corp | Farmington, NM 87499 | Oil & Gas Operator | Sep 2025 |
| 24 | Duncan Energy Companyuncan Energy Company | Denver, CO 80210 | Oil & Gas Operator | Jun 1995 |
| 25 | Duncan Oil Inc | Denver, CO 80210 | Oil & Gas Operator | Jun 2016 |
| 26 | Duncan, Raymond T | Denver, CO 80210 | Oil & Gas Operator | Feb 1996 |
| 27 | Dyco Petroleum Corporation | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2015 |