| 1 | D&S Oil & Gas Operators, Inc. | | Oil & Gas Operator | Dec 2020 |
| 2 | D. B. Braddock | | Oil & Gas Operator | Jan 1986 |
| 3 | D. B. Braddock-Kisatchie Res. | | Oil & Gas Operator | Jan 1985 |
| 4 | D. L. Gish | | Oil Operator | Mar 1992 |
| 5 | D. L. Gish Oil Partnership | | Oil Operator | Feb 1989 |
| 6 | D. L. Gish Oil, Inc. | | Oil Operator | Jul 1998 |
| 7 | D. L. Gish, Inc. | | Oil Operator | Jun 1990 |
| 8 | Dal-Long Oil Company | Longview, TX 75608 | Oil Operator | Feb 2001 |
| 9 | Dallas Production, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2021 |
| 10 | Damson Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Mar 2005 |
| 11 | David A. Robinson | | Oil Operator | Jan 1999 |
| 12 | David Crow | | Oil & Gas Operator | Nov 1985 |
| 13 | DCP Midstream, LLC | | Oil Operator | Jun 2016 |
| 14 | DDC & T Operating Company, Inc | | Oil & Gas Operator | Jul 2005 |
| 15 | Delta Petroleum Inc | Houston, TX 77269-1007 | Oil & Gas Operator | May 2009 |
| 16 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 17 | Dewey E. Williams | | Oil Operator | Nov 1978 |
| 18 | Dewey Williams | | Oil Operator | Mar 1992 |
| 19 | Dews Production LLC | Magnolia, AR 71753 | Oil & Gas Operator | Jan 2025 |
| 20 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Oct 2025 |
| 21 | Divine'S Service & Repairs Inc | | Oil & Gas Operator | Mar 1997 |
| 22 | Don Townes | | Oil Operator | Sep 2000 |
| 23 | Doran & Braddock & Nelson Petr | | Oil Operator | Feb 1982 |
| 24 | Dorcheat Oil & Gas, LLC | | Oil & Gas Operator | Dec 2024 |
| 25 | Dorchester Exploration, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Aug 2001 |
| 26 | Dossie Dews | | Oil & Gas Operator | Dec 2024 |
| 27 | Double Eagle Petroleum Corp | Evansville, IN 47725 | Oil & Gas Operator | Oct 2025 |
| 28 | Dual Energy, Inc. | | Oil & Gas Operator | Oct 2022 |
| 29 | Duke Energy Field Services Inc | | Oil Operator | Mar 2000 |
| 30 | Duke Energy Field Services LLC | | Oil Operator | Dec 2006 |