| 1 | Dallas Production, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2021 |
| 2 | Daniel Mineral Development, Inc. | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2007 |
| 3 | Decker Operating Co., L.L.C. | Houston, TX 77008 | Oil & Gas Operator | Oct 2025 |
| 4 | Deguello Operating LLC | Kilgore, TX 75663 | Oil & Gas Operator | Oct 2025 |
| 5 | Devon Energy Operating Co., L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2009 |
| 6 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 7 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 8 | Diasu Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 9 | DNR Oil And Gas, Inc. | Englewood, CO 80155 | Oil & Gas Operator | Aug 2025 |
| 10 | Dominion Minerals Corporation | Houston, TX 77014 | Oil & Gas Operator | Nov 2009 |
| 11 | Douglas Petroleum Inc. | Spring, TX 77379 | Oil & Gas Operator | Nov 2010 |
| 12 | Dynamic Petroleum Res., Inc. | Houston, TX 77068 | Oil & Gas Operator | Jul 1994 |