| 1 | D&S Oil & Gas Operators, Inc. | | Oil & Gas Operator | Dec 2020 |
| 2 | D. W. Tanner | | Oil & Gas Operator | May 2000 |
| 3 | Dal-Long Oil Company | Longview, TX 75608 | Oil Operator | Feb 2001 |
| 4 | Dallas Production, Inc. | Dallas, TX 75206 | Oil & Gas Operator | Mar 2021 |
| 5 | David Crow | | Oil & Gas Operator | Nov 1985 |
| 6 | DCP Midstream, LLC | | Oil Operator | Jun 2016 |
| 7 | Dean Petroleum | | Oil & Gas Operator | Jun 2000 |
| 8 | Deblin Oil & Gas, Inc | | Oil & Gas Operator | Aug 1995 |
| 9 | Deep South Production | | Oil Operator | Dec 2023 |
| 10 | Delhi Gas Pipeline Corporation | Palestine, TX 75802 | Oil & Gas Operator | Feb 1998 |
| 11 | Delphi International, Inc. | Tulsa, OK 74104 | Oil Operator | Jul 2025 |
| 12 | Delta Petroleum Corp Of Co | | Oil & Gas Operator | Oct 2010 |
| 13 | Despot, Inc. | | Oil & Gas Operator | Mar 1983 |
| 14 | Diamond Drilling Co. | | Oil Operator | Apr 1983 |
| 15 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Oct 2025 |
| 16 | Dome Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 2016 |
| 17 | Dominion Minerals Corporation | Houston, TX 77014 | Oil & Gas Operator | Nov 2009 |
| 18 | Dorcheat Oil & Gas, LLC | | Oil & Gas Operator | Dec 2024 |
| 19 | Dossie Dews | | Oil & Gas Operator | Dec 2024 |
| 20 | Dual Energy, Inc. | | Oil & Gas Operator | Oct 2022 |
| 21 | Dubach Gas Company | | Oil Operator | May 2003 |
| 22 | Duer Wagner & Company | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1998 |
| 23 | Duke Energy Field Services Inc | | Oil Operator | Mar 2000 |
| 24 | Duke Energy Field Services LLC | | Oil Operator | Dec 2006 |