| 101 | DBL DRLG.&Prod. Services, Inc. | | Oil & Gas Operator | Jul 1997 |
| 102 | DCP Midstream, LLC | | Oil Operator | Jun 2016 |
| 103 | DCP, Inc. | | Oil & Gas Operator | Jun 1990 |
| 104 | DDC & T Operating Company, Inc | | Oil & Gas Operator | Jul 2005 |
| 105 | Dean Enterprises, Inc. | | Oil & Gas Operator | Jun 2019 |
| 106 | Dean Petroleum | | Oil & Gas Operator | Jun 2000 |
| 107 | Debbie Carroll | | Oil & Gas Operator | Apr 1999 |
| 108 | Debeaux - Flores | | Oil & Gas Operator | Jan 2025 |
| 109 | Deblin Oil & Gas, Inc | | Oil & Gas Operator | Aug 1995 |
| 110 | Deblin Operating LTD | | Oil & Gas Operator | Jan 1997 |
| 111 | Deck Oil Company | Tulsa, OK 74101 | Oil & Gas Operator | Jun 2020 |
| 112 | Decker & Associates | | Oil & Gas Operator | Mar 1991 |
| 113 | Decker Operating Co., L.L.C. | Houston, TX 77008 | Oil & Gas Operator | Jul 2025 |
| 114 | Deco | Kilgore, TX 75662 | Oil & Gas Operator | Jan 1999 |
| 115 | Deco Oil Co. | | Oil Operator | Oct 2013 |
| 116 | Deep South Production | | Oil Operator | Dec 2023 |
| 117 | Dees Production LLC | | Oil Operator | Dec 2024 |
| 118 | Dekasco, Inc. | | Oil & Gas Operator | May 1990 |
| 119 | Delbert A. Dodson | | Oil Operator | Aug 2002 |
| 120 | Delhi Gas Pipeline Corporation | Palestine, TX 75802 | Oil & Gas Operator | Feb 1998 |
| 121 | Delmar Operating, Inc. | Houston, TX 77010 | Oil & Gas Operator | Oct 1996 |
| 122 | Delphi International, Inc. | Tulsa, OK 74104 | Oil Operator | Apr 2025 |
| 123 | Delta Development Co. Inc. | | Oil & Gas Operator | Dec 1988 |
| 124 | Delta Energy Resources, Inc. | | Oil & Gas Operator | Jun 1990 |
| 125 | Delta Expl.& Development Corp. | | Oil & Gas Operator | Jan 2025 |
| 126 | Delta Exploration Company Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 127 | Delta Oil Corp | | Oil & Gas Operator | Dec 2005 |
| 128 | Delta Operating Company | | Oil Operator | Mar 1987 |
| 129 | Delta Operating Corporation | | Oil & Gas Operator | Feb 2024 |
| 130 | Delta Petroleum Corp Of Co | | Oil & Gas Operator | Oct 2010 |
| 131 | Delta Petroleum Inc | Houston, TX 77269-1007 | Oil & Gas Operator | May 2009 |
| 132 | Delta Production Services, LLC | | Oil & Gas Operator | Aug 2002 |
| 133 | Delta Royalties LLC | | Oil & Gas Operator | Dec 2024 |
| 134 | Deltaus Corporation | | Oil & Gas Operator | Oct 1985 |
| 135 | Deminex U.S. Oil Company | | Oil & Gas Operator | Jan 1998 |
| 136 | Demiran Production, Inc. | | Oil Operator | Mar 2008 |
| 137 | Dempsey & Rowe | | Oil Operator | Aug 1986 |
| 138 | Denali Oil & Gas Management, LLC | Houston, TX 77060 | Oil & Gas Operator | Dec 2012 |
| 139 | Denbury Management, Inc. | Dallas, TX 75252 | Oil & Gas Operator | Dec 1999 |
| 140 | Denbury Offshore, Inc. | | Oil & Gas Operator | Nov 2004 |
| 141 | Denbury Onshore, LLC | Plano, TX 75024 | Oil & Gas Operator | Jul 2025 |
| 142 | Denbury Resources Inc. | Plano, TX 75024 | Oil & Gas Operator | Dec 2003 |
| 143 | Denex, Inc. | | Oil & Gas Operator | Jul 1983 |
| 144 | Denovo Oil & Gas, Inc. | Houston, TX 77210 | Oil & Gas Operator | May 1995 |
| 145 | Derrick Petroleum Inc | Bladensburg, OH 43005 | Oil & Gas Operator | Dec 2024 |
| 146 | Desco Oil Company | Houston, TX 77056 | Oil & Gas Operator | Feb 2017 |
| 147 | Desco-Medders | | Oil & Gas Operator | Jun 1984 |
| 148 | Desoto Gas Corporation | | Oil & Gas Operator | Oct 1986 |
| 149 | Desoto Gas Prod Co Inc-Zadeck | | Gas Operator | Jan 1990 |
| 150 | Desoto Gas Producing Co. Inc | | Oil & Gas Operator | Jan 1990 |
| 151 | Desoto Oil & Gas Corporation | | Oil & Gas Operator | Dec 1990 |
| 152 | Desperation Oil & Gas Co. | | Gas Operator | Jan 1989 |
| 153 | Despot Expl. Inc-Serio Expl Co | | Oil & Gas Operator | Apr 1990 |
| 154 | Despot Exploration, Inc. | | Oil & Gas Operator | Apr 1990 |
| 155 | Despot Production Company | | Oil & Gas Operator | May 1983 |
| 156 | Despot, Inc. | | Oil & Gas Operator | Mar 1983 |
| 157 | Destin Operating Company, Inc. | | Oil & Gas Operator | Jan 2023 |
| 158 | Destin Resources LLC | | Gas Operator | Jul 2018 |
| 159 | Devon Corporation | | Oil Operator | Oct 1981 |
| 160 | Devon Energy Corp (Nevada) | Oklahoma City, OK 73102 | Oil & Gas Operator | Feb 2017 |
| 161 | Devon Energy Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Dec 2009 |
| 162 | Devon Energy Operating Co., L.P. | Oklahoma City, OK 73102 | Oil & Gas Operator | Jun 2009 |
| 163 | Devon Energy Production Company LP | Oklahoma City, OK 73102 | Oil & Gas Operator | Jul 2025 |
| 164 | Devon Louisiana Corporation | Houston, TX 77002 | Oil & Gas Operator | Oct 2019 |
| 165 | Devon SFS Operating Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2008 |
| 166 | Dew Oil And Gas Co.,Inc. | | Oil & Gas Operator | Dec 1989 |
| 167 | Dewco Oil | | Oil Operator | Jun 1996 |
| 168 | Dewey E. Williams | | Oil Operator | Nov 1978 |
| 169 | Dewey White Etal | | Oil & Gas Operator | Dec 1987 |
| 170 | Dewey Williams | | Oil Operator | Mar 1992 |
| 171 | Dews Production LLC | Magnolia, AR 71753 | Oil & Gas Operator | Dec 2024 |
| 172 | Dexco, Inc. | | Oil & Gas Operator | May 1990 |
| 173 | DGH Petroleum, Inc. | | Oil & Gas Operator | Aug 2011 |
| 174 | Di Energy Inc. | Houston, TX 77067 | Oil & Gas Operator | Jan 2004 |
| 175 | Diablo Oil Corp. | | Oil & Gas Operator | Apr 1989 |
| 176 | Diamar Oil Company, Inc. | | Oil Operator | Nov 1983 |
| 177 | Diamex Company | | Oil & Gas Operator | Oct 1982 |
| 178 | Diamond D Operating | | Oil & Gas Operator | Apr 1995 |
| 179 | Diamond Drilling Co. | | Oil Operator | Apr 1983 |
| 180 | Diamond S Operating Co. | | Oil & Gas Operator | Oct 1992 |
| 181 | Diamond Shamrock Corp | Amarillo, TX 79105 | Oil & Gas Operator | Jan 1987 |
| 182 | Diamond Shamrock Expl. Co. | | Oil & Gas Operator | Jun 1987 |
| 183 | Diasu Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2016 |
| 184 | Dilligas, Inc. | | Oil Operator | May 1990 |
| 185 | Dimension Energy Co., L.L.C. | | Oil & Gas Operator | Dec 2024 |
| 186 | Discovery Energy, LLC | | Oil Operator | Jan 2007 |
| 187 | Discovery Operating, LLC | | Oil & Gas Operator | Oct 2023 |
| 188 | Discus Oil Corporation | | Oil & Gas Operator | Dec 2002 |
| 189 | Ditta Exploration Co., Inc. | | Oil & Gas Operator | Feb 1990 |
| 190 | Diversified Energy Investments | | Oil & Gas Operator | May 2009 |
| 191 | Diversified Natural Res., Inc. | | Oil Operator | May 2000 |
| 192 | Diversified Production LLC | Keithville, LA 71047 | Oil & Gas Operator | Jul 2025 |
| 193 | Divine'S Service & Repairs Inc | | Oil & Gas Operator | Mar 1997 |
| 194 | Dixie Operating Company | Spring, TX 77379 | Oil & Gas Operator | Dec 2002 |
| 195 | Dixie Well Service, Inc. | | Oil & Gas Operator | Jul 1995 |
| 196 | Dixon Management Corp. | | Oil & Gas Operator | May 1984 |
| 197 | DKM Resources, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Sep 2011 |
| 198 | DLB Oil & Gas, Inc. | Big Lake, TX 76932 | Oil & Gas Operator | Jul 2025 |
| 199 | DMS Oil Company | Houston, TX 77042 | Oil & Gas Operator | May 2025 |
| 200 | Dna Petroleum Inc. | | Oil Operator | Dec 2004 |