| 1 | D & D DRLG Co & Saye Oil Co | | Oil Operator | Apr 1982 |
| 2 | D & J Producing Company | | Oil Operator | Sep 2006 |
| 3 | D. A. Biglane | | Oil & Gas Operator | Feb 1990 |
| 4 | Dale Expl Co & R. A. Campbell | | Oil Operator | Nov 1995 |
| 5 | Dale Exploration Company | | Oil & Gas Operator | May 2004 |
| 6 | Dale O. Reese | | Oil Operator | Nov 1989 |
| 7 | Dale O. Reese, Inc. | | Oil Operator | Jul 1997 |
| 8 | Dalton J. Woods | | Oil & Gas Operator | Dec 1985 |
| 9 | Daniel Oil Company | | Oil & Gas Operator | Jan 1983 |
| 10 | Dave Easom Production Co. Inc. | | Oil & Gas Operator | May 2000 |
| 11 | David New Operating Co., Inc. | | Oil & Gas Operator | Feb 1999 |
| 12 | Davis & Kaiser Operating, Inc. | | Oil Operator | May 2004 |
| 13 | Day Dreams Resources, LLC | | Oil & Gas Operator | Jul 2025 |
| 14 | Deblin Operating LTD | | Oil & Gas Operator | Jan 1997 |
| 15 | Deco Oil Co. | | Oil Operator | Oct 2013 |
| 16 | Denbury Management, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 1999 |
| 17 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Oct 2025 |
| 18 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 19 | Dixie Operating Company | Spring, TX 77379 | Oil & Gas Operator | Dec 2002 |
| 20 | Domestic Oil Producers,Inc. | | Oil Operator | Oct 1998 |
| 21 | Double J Operating Company, Inc. | San Antonio, TX 78205 | Oil Operator | Jan 2008 |