| 1 | D & D Exploration Co. Et Al | | Oil Operator | Feb 1988 |
| 2 | D. A. Biglane Operating Co Et Al | | Oil Operator | Feb 2004 |
| 3 | Dale Exploration Co. | | Oil & Gas Operator | May 2004 |
| 4 | Dallas Production Company LLC | Dallas, TX 75206 | Oil & Gas Operator | Nov 2025 |
| 5 | Dapsco, Inc. | | Oil & Gas Operator | Dec 1976 |
| 6 | David New Operating Co. Inc. | | Oil & Gas Operator | Feb 1999 |
| 7 | David New Operating-Belle Exp | | Oil Operator | Mar 1990 |
| 8 | Day Dreams Resources, LLC | | Oil & Gas Operator | Aug 2025 |
| 9 | Deeprock Disposal Services, LLC | | Oil & Gas Operator | Sep 1991 |
| 10 | Deepwell Co | | Oil Operator | Jul 1989 |
| 11 | Del Oil & Gas Corp | | Oil Operator | Jul 1981 |
| 12 | Delphi Oil Inc. | | Oil & Gas Operator | Sep 2025 |
| 13 | Delta Petroleum Inc | Houston, TX 77269-1007 | Oil & Gas Operator | May 2009 |
| 14 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Nov 2025 |
| 15 | Denbury Resources Inc. | Plano, TX 75024 | Oil & Gas Operator | Dec 2003 |
| 16 | Diamond Onshore Production, L. L. C. | | Oil & Gas Operator | Sep 2005 |
| 17 | Diamondhead Oil Co., LLC | | Oil & Gas Operator | Aug 2025 |
| 18 | Dixie Operating Company | Spring, TX 77379 | Oil & Gas Operator | Dec 2002 |
| 19 | Domestic Oil Producers | | Oil Operator | Oct 1980 |
| 20 | Domestic Oil Production | | Oil & Gas Operator | Oct 1989 |
| 21 | Double J Operating Company, Inc. | San Antonio, TX 78205 | Oil Operator | Jan 2008 |
| 22 | Duer Wagner & Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1998 |
| 23 | Duncan-Taylor & Schumacher | | Oil & Gas Operator | Nov 1987 |
| 24 | Durango Operating LLC | Madison, MS 39110 | Oil & Gas Operator | Sep 2025 |