| 101 | Temagami Oil & Gas LTD | | Oil & Gas Operator | May 2007 |
| 102 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Sep 2025 |
| 103 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 104 | Texas American Oil Corporation | Midland, TX 79701 | Oil & Gas Operator | Jan 2001 |
| 105 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 106 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 107 | Three Forks Resources, LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Dec 2025 |
| 108 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 109 | Tipperary Oil & Gas Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2014 |
| 110 | Trigg Drilling Company Inc | Oklahoma City, OK 73105 | Oil & Gas Operator | Jan 2013 |
| 111 | U V Industries | | Oil & Gas Operator | Jan 1993 |
| 112 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 113 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 114 | Urban Oil & Gas Group, LLC | Plano, TX 75074 | Oil & Gas Operator | Dec 2025 |
| 115 | Valkyrie Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 116 | Viking Resources Corp | Deerfield, OH 44411-0160 | Oil & Gas Operator | Dec 2007 |
| 117 | Voyager Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | May 2006 |
| 118 | Wagner & Brown Limited Partnership | Midland, TX 79701 | Oil & Gas Operator | Feb 2013 |
| 119 | Wallway M J | Casper, WY 82601 | Oil & Gas Operator | Jan 1993 |
| 120 | Washakie Energies Company | Worland, WY 82401 | Oil & Gas Operator | Dec 2019 |
| 121 | Washakie Oil Company | | Oil & Gas Operator | Dec 1989 |
| 122 | Weaver Dale Inc | Powell, WY 82435 | Oil Operator | Apr 2005 |
| 123 | Weaver Oil Inc | | Oil & Gas Operator | Oct 2011 |
| 124 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Oct 2025 |
| 125 | White Rock Oil & Gas, LLC | Plano, TX 75024 | Oil & Gas Operator | Dec 2025 |
| 126 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2025 |
| 127 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 128 | Wyoil Corp | Buffalo, WY 82834 | Oil Operator | Aug 2025 |
| 129 | Wyoming Resources Corporation | Rapid City, SD 57702 | Oil & Gas Operator | Oct 2018 |