| 1 | D & B Energy Corporation | San Antonio, TX 78264 | Oil Operator | Oct 2025 |
| 2 | D & P Operating & Prod. Corp. | Cedar Park, TX 78613 | Oil & Gas Operator | Dec 2003 |
| 3 | D. O. G. Operating, LLC | Port Aransas, TX 78373 | Oil & Gas Operator | Oct 2025 |
| 4 | D.Y. Exploration, Inc. | Boise, ID 83705 | Oil & Gas Operator | Oct 2025 |
| 5 | Daf Operating, LLC | Houston, TX 77005 | Oil & Gas Operator | Oct 2025 |
| 6 | Dakota Oil Company | Hebbronville, TX 78361 | Oil & Gas Operator | Oct 2025 |
| 7 | Dale Operating Company | Dallas, TX 75201 | Oil & Gas Operator | Oct 2025 |
| 8 | Dalen Resources Oil & Gas Co. | Dallas, TX 75206 | Oil & Gas Operator | Jun 2010 |
| 9 | Dallas Petroleum Group, LLC | Dallas, TX 75379 | Oil & Gas Operator | Oct 2025 |
| 10 | Dantex Oil & Gas, Inc. | Dallas, TX 75225 | Oil & Gas Operator | Aug 2003 |
| 11 | Dark Horse Producing Of TX, L.P. | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 12 | Dartex Energy Corporation | Austin, TX 78746 | Oil & Gas Operator | Oct 2025 |
| 13 | Davis Petroleum Corp. | Houston, TX 77027 | Oil & Gas Operator | Oct 2025 |
| 14 | Davis, Tommy | Hebbronville, TX 78361 | Oil & Gas Operator | Jun 1995 |
| 15 | Daystar Operating Company, LLC | Austin, TX 78750 | Oil & Gas Operator | Apr 2008 |
| 16 | Del Petroleum Corporation | Dallas, TX 75219 | Oil & Gas Operator | Jan 2012 |
| 17 | Delaware Davis Petroleum Corp. | Houston, TX 77056 | Oil & Gas Operator | Jan 2000 |
| 18 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 19 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Oct 2025 |
| 20 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 21 | Dewbre Petroleum Corporation | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 22 | Dewbre, Jerry C., Trustee | Corpus Chrsti, TX 78404 | Oil & Gas Operator | Oct 2025 |
| 23 | Diamondback Operating, LP | Tulsa, OK 74132 | Gas Operator | Oct 2025 |
| 24 | Dinero Oil Corporation | Corpus Chrsti, TX 78460 | Oil & Gas Operator | Nov 1999 |
| 25 | Dirks, R.W. Pet. Eng. Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Jul 1999 |
| 26 | Dirnett, Inc. | Tuleta, TX 78162 | Oil & Gas Operator | Oct 2025 |
| 27 | Discorbis Oil Company | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2019 |
| 28 | Discovery Energy Corp. CC | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2025 |
| 29 | Discovery Petroleum, L.L.C. | Alice, TX 78333 | Oil & Gas Operator | Oct 2025 |
| 30 | DKW Energy, Inc. | Sherman Oaks, CA 91403 | Oil & Gas Operator | Oct 2025 |
| 31 | DML Exploration, Inc. | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 32 | Dogwood Operating Company, Inc. | Houston, TX 77069 | Oil & Gas Operator | Oct 2025 |
| 33 | Dolphin Petroleum | Alice, TX 78333 | Oil & Gas Operator | Jun 2008 |
| 34 | Dominion Exploration & Production Inc | Houston, TX 77060 | Oil & Gas Operator | Apr 2015 |
| 35 | Dominion Oklahoma Texas E&P, Inc | Richmond, VA 23219 | Oil & Gas Operator | Sep 2018 |
| 36 | Donna-Lynne Oil Co. | George West, TX 78022 | Oil & Gas Operator | Jun 2018 |
| 37 | Dorado Oil Company | Corpus Chrsti, TX 78403 | Oil & Gas Operator | Oct 2013 |
| 38 | Double Play Oil & Gas, Inc | Portland, TX 78374 | Oil & Gas Operator | Oct 2025 |
| 39 | Dreyfus, Louis Natural Gas Corp | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2001 |
| 40 | Drillers Energy Search, Inc | Denver, CO 80202 | Oil & Gas Operator | Aug 1996 |
| 41 | Dugger, Glenn | Alice, TX 78332 | Oil & Gas Operator | Nov 2013 |
| 42 | Dunigan Petroleum, Inc. | Dallas, TX 75201 | Oil & Gas Operator | Aug 2003 |
| 43 | Duster Production, Inc. | Refugio, TX 78377 | Oil & Gas Operator | Oct 2011 |
| 44 | Duval Gas Gathering Corporation | Austin, TX 78711 | Oil & Gas Operator | Oct 2025 |
| 45 | Dynamic Production, Inc. | Fort Worth, TX 76106 | Oil & Gas Operator | Oct 2025 |