| 1 | D.C. Oil | Natalia, TX 78059 | Oil Operator | May 2025 |
| 2 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 3 | Dawsey Operating Company | Georgetown, TX 78628 | Oil & Gas Operator | Mar 2016 |
| 4 | Daylight Petroleum LLC | Houston, TX 77052 | Oil & Gas Operator | May 2025 |
| 5 | DCP Operating Co LP | Houston, TX 77042 | Oil & Gas Operator | Jan 2025 |
| 6 | Deep Rock Resources, Inc. | Dallas, TX 75206 | Oil & Gas Operator | May 2025 |
| 7 | Delcar, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | Oct 1995 |
| 8 | Delgado, Emil A | San Antonio, TX 78223 | Oil & Gas Operator | Sep 2016 |
| 9 | Delong, Horace | Pleasanton, TX 78064 | Oil & Gas Operator | May 2025 |
| 10 | Delray Oil, Inc. | San Antonio, TX 78209 | Oil & Gas Operator | May 2025 |
| 11 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 12 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 13 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | May 2025 |
| 14 | Diamond Energy Services, LP | Tulsa, OK 74103 | Oil Operator | May 2025 |
| 15 | Dickson Petroleum, Inc. | Midland, TX 79710 | Oil & Gas Operator | May 2000 |
| 16 | Dirnett, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | May 2025 |
| 17 | Discorbis Oil Company | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2019 |
| 18 | Discovery Petroleum, L.L.C. | Alice, TX 78333 | Oil & Gas Operator | May 2025 |
| 19 | DKW Energy, Inc. | Sherman Oaks, CA 91403 | Oil & Gas Operator | May 2025 |
| 20 | Dodson, Inc. | San Antonio, TX 78232 | Oil & Gas Operator | Oct 1998 |
| 21 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Dec 2014 |
| 22 | Dorchester Operating Company LLC | Refugio, TX 78377 | Oil & Gas Operator | May 2025 |
| 23 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | May 2025 |
| 24 | Drachen Oil Company | San Antonio, TX 78258 | Oil & Gas Operator | May 2025 |
| 25 | Duplantis Energy, LLC | Pleasanton, TX 78064 | Oil Operator | May 2025 |
| 26 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | May 2025 |