| 101 | Banks Operating Company | | Oil & Gas Operator | Jul 1989 |
| 102 | Bannon Energy Inc | Houston, TX 77068 | Oil & Gas Operator | Jun 1998 |
| 103 | Banta And Haigh | Aurora, CO 80014 | Oil & Gas Operator | Feb 1998 |
| 104 | Barbe D F | Recluse, WY 82725 | Oil & Gas Operator | Dec 2000 |
| 105 | Barn Owls LLC | | Oil & Gas Operator | Oct 2025 |
| 106 | Barrel Springs Development Corp | Denver, CO 80202 | Oil & Gas Operator | Oct 1986 |
| 107 | Barrett Patrick | | Oil & Gas Operator | Apr 1988 |
| 108 | Basf Corporation | Houston, TX 77027 | Oil & Gas Operator | Nov 1992 |
| 109 | Basin Oil & Gas Operating LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Dec 2025 |
| 110 | Basin Resources Corporation | Fair Oaks Ranch, TX 78015 | Oil Operator | May 2013 |
| 111 | Bass Enterprises Production Co | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 2006 |
| 112 | Bass Petroleum Inc | Austin, TX 78716 | Oil & Gas Operator | Dec 2025 |
| 113 | Bataa Oil Inc | Arvada, CO 80005 | Oil & Gas Operator | Oct 2025 |
| 114 | Bates Creek Oil | | Oil Operator | Dec 1986 |
| 115 | Bayless Robert L Producer | Denver, CO 80293 | Oil & Gas Operator | Sep 2003 |
| 116 | Bayswater Exploration & Production LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 117 | Baytex Energy USA LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2014 |
| 118 | Bce-Mach LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Nov 2025 |
| 119 | Bear Oil And Gas Inc | Las Vegas, NV 89107 | Oil & Gas Operator | Jul 2016 |
| 120 | Bearcat Energy LLC (Colorado) | Denver, CO 80202 | Oil & Gas Operator | May 2022 |
| 121 | Bearcat Petroleum Inc | | Oil Operator | Dec 1991 |
| 122 | Beard Oil Company | Oklahoma City, OK 73102 | Oil & Gas Operator | Aug 2013 |
| 123 | Beartooth Oil & Gas Company | Billings, MT 59103 | Oil & Gas Operator | Nov 2025 |
| 124 | Belco Energy Corp. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2015 |
| 125 | Belden & Blake Corporation | North Canton, OH 44720 | Oil & Gas Operator | Dec 2016 |
| 126 | Bell Resources Inc | Billings, MT 59104 | Oil & Gas Operator | Jun 2016 |
| 127 | Bellevue Resources Inc | Lakewood, CO 80235 | Oil & Gas Operator | Feb 2009 |
| 128 | Benchmark Energy LLC | Pratt, KS 67124 | Oil & Gas Operator | Sep 2023 |
| 129 | Bennett Petroleum Corporation | Denver, CO 80203 | Oil Operator | Jun 1985 |
| 130 | Benson-Montin-Greer DRLG Corp | Farmington, NM 87402 | Oil & Gas Operator | Dec 2025 |
| 131 | Berco Resources LLC | Denver, CO 80206 | Oil & Gas Operator | Sep 2009 |
| 132 | Beren Corporation | Wichita, KS 67206 | Oil & Gas Operator | Dec 2025 |
| 133 | Berenergy Corporation | Denver, CO 80217 | Oil & Gas Operator | Dec 2025 |
| 134 | Berry Petroleum Company | Denver, CO 80202 | Oil & Gas Operator | Feb 2014 |
| 135 | Beta Oil Company Inc | Oklahoma City, OK 73157-2958 | Oil & Gas Operator | Sep 2025 |
| 136 | Betop Inc | Ojai, CA 83203 | Oil & Gas Operator | Dec 1996 |
| 137 | BHB Oil Partners LLC | Powell, WY 82435 | Oil Operator | Oct 2025 |
| 138 | BHP Petroleum (USA) Inc | | Oil & Gas Operator | Mar 1993 |
| 139 | BHP Petroleum Company Inc | Houston, TX 77057 | Oil & Gas Operator | Jun 2016 |
| 140 | Big Basin Petroleum LLC | Gillette, WY 82717 | Oil & Gas Operator | Oct 2008 |
| 141 | Big Chief Exploration | Palisades, CO 81526 | Oil & Gas Operator | Oct 1993 |
| 142 | Big Muddy Operating LLC | Casper, WY 82602 | Oil Operator | Oct 2025 |
| 143 | Big Piney Oil & Gas Company | Dallas, TX 75206 | Oil & Gas Operator | Sep 1992 |
| 144 | Big Wells Energy Corp | Katy, TX 77494 | Oil & Gas Operator | Sep 2019 |
| 145 | Bill Barrett Corporation | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 146 | Bing Harold C | Newcastle, WY 82701 | Oil Operator | Jun 1992 |
| 147 | Bird Oil Corporation | | Oil & Gas Operator | Jul 1992 |
| 148 | Bison IV Operating LLC | | Oil & Gas Operator | Oct 2025 |
| 149 | Bitterroot Energy Partners LLC | | Oil & Gas Operator | Nov 2025 |
| 150 | Black Bank LLC | Billings, MT 59103 | Oil Operator | Oct 2025 |
| 151 | Black Bear Oil Corporation | Las Vegas, NV 89128 | Oil & Gas Operator | Oct 2025 |
| 152 | Black Coal Resources Company | Fort Washakie, WY 82514 | Oil & Gas Operator | Dec 1991 |
| 153 | Black Diamond Energy Inc | Pittsburgh, PA 15237 | Gas Operator | May 2016 |
| 154 | Black Diamond Energy Of Delaware Inc | Buffalo, WY 82834 | Oil & Gas Operator | Oct 2025 |
| 155 | Black Gold Services Inc | Casper, WY 82644 | Oil & Gas Operator | Oct 2025 |
| 156 | Black Hawk Resources Corporation | Denver, CO 80202 | Oil Operator | Mar 1986 |
| 157 | Black Hills Exploration & Production Inc | Newcastle, WY 82701 | Oil & Gas Operator | Mar 2018 |
| 158 | Black Hills Wyoming Gas LLC | Rapid City, SD 57709 | Gas Operator | Nov 2025 |
| 159 | Black Jack Oil Co Inc | Holliday, TX 76366 | Oil & Gas Operator | Oct 2025 |
| 160 | Black Thunder Oil LLC | Gillette, WY 82717 | Oil & Gas Operator | Sep 2025 |
| 161 | Blackjack Oil, Inc. | Las Vegas, NV 89128 | Oil & Gas Operator | Nov 2019 |
| 162 | Blackstone Operating Inc | Red Lodge, MT 59068 | Gas Operator | Nov 2009 |
| 163 | Blake Production LLC | Gillette, WY 82717 | Oil & Gas Operator | Oct 2025 |
| 164 | Blue Spruce Operating LLC | Pinedale, WY 82941 | Oil & Gas Operator | Nov 2025 |
| 165 | Blue Tip Energy Wyoming Inc | Houston, TX 77284 | Oil Operator | Jun 2016 |
| 166 | Bluebonnet Energy Corporation | Englewood, CO 80112 | Oil & Gas Operator | Sep 2015 |
| 167 | Boelens Well Service LLC | Thermopolis, WY 82443 | Oil Operator | Dec 1999 |
| 168 | Boggy Creek Production | Newcastle, WY 82701 | Oil & Gas Operator | Apr 2012 |
| 169 | Borchert R V | Sidney, NE 69162 | Oil Operator | Apr 2009 |
| 170 | Bowden Energy Company Inc | Gillette, WY 82716 | Oil & Gas Operator | Aug 2025 |
| 171 | Bower Properties LLC | Worland, WY 82401 | Oil & Gas Operator | Aug 2005 |
| 172 | Bowers Oil & Gas, Inc. | Grand Junction, CO 81505-1097 | Oil & Gas Operator | Nov 2022 |
| 173 | Box H Resources | Cody, WY 82414 | Oil & Gas Operator | Dec 2007 |
| 174 | Boyd Exploration | | Oil & Gas Operator | Dec 1986 |
| 175 | BP America Production Company | Denver, CO 80202 | Oil & Gas Operator | Nov 2025 |
| 176 | BP Exploration Inc | | Oil & Gas Operator | May 1993 |
| 177 | BP Production Company LLC | Evergreen, CO 80439 | Oil Operator | Jul 2001 |
| 178 | Braden Oil | | Oil & Gas Operator | Mar 2007 |
| 179 | Braden-Deem Inc | Wichita, KS 67226 | Oil & Gas Operator | Oct 2025 |
| 180 | Bradford Oil Company | Denver, CO 80249 | Oil & Gas Operator | Oct 2025 |
| 181 | Bradley Jr Jack C | Casper, WY 82601 | Oil & Gas Operator | Apr 2009 |
| 182 | Bradley SR Jack C | Newcastle, WY 82701 | Oil Operator | Jun 2010 |
| 183 | Brannon Oil & Gas Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 2013 |
| 184 | Breck Operating Corp. | Breckenridge, TX 76424 | Oil & Gas Operator | Nov 2025 |
| 185 | Brehm Investment Group Inc | | Oil Operator | Jul 1991 |
| 186 | Brehm Oil | MT. Vernon, IL 62864 | Oil Operator | Jan 1986 |
| 187 | Breitburn Energy Company LLC | Lakewood, CO 80227 | Oil Operator | Aug 2011 |
| 188 | Breitburn Operating LP | Keithville, LA 71047 | Oil & Gas Operator | Dec 2025 |
| 189 | Brent Exploration | | Oil & Gas Operator | Dec 1993 |
| 190 | Bridger Petroleum Corp | | Oil & Gas Operator | Oct 1999 |
| 191 | Bridwell Oil Company | Wichita Falls, TX 76307 | Oil & Gas Operator | Dec 2025 |
| 192 | Brigham Oil & Gas, L.P. | Austin, TX 78730 | Oil & Gas Operator | Oct 2015 |
| 193 | Bright Rock Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Nov 2024 |
| 194 | Brighton Energy, L.L.C. | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2015 |
| 195 | Briscoe Petroleum, LLC | Sheridan, WY 82801 | Oil & Gas Operator | Nov 2025 |
| 196 | Bristol Resources Corporation | Tulsa, OK 74170 | Oil & Gas Operator | Feb 2022 |
| 197 | Bronco Oil & Gas Co | Casper, WY 82602 | Oil & Gas Operator | Oct 1987 |
| 198 | Brooks Exploration Inc | Denver, CO 80293 | Oil & Gas Operator | Mar 2001 |
| 199 | Brower Oil & Gas Inc | Jenks, OK 74037 | Oil & Gas Operator | Nov 2022 |
| 200 | Brown & Bickerstaff | | Oil & Gas Operator | Oct 1991 |