| 201 | Reserve Oil & Gas Company | | Oil & Gas Operator | Jul 1981 |
| 202 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 203 | Reunion Energy Company | Houston, TX 77056 | Oil & Gas Operator | May 1996 |
| 204 | Rim Operating, Inc. | Englewood, CO 80112 | Oil & Gas Operator | Apr 2025 |
| 205 | Rio Blanco Energy, Inc. | Littleton, CO 80121 | Oil & Gas Operator | Oct 2002 |
| 206 | River City Resources, Inc. | Tulsa, OK 74119 | Oil & Gas Operator | Nov 1997 |
| 207 | Rock Creek Resources LLC | Englewood, CO 80112 | Oil & Gas Operator | Dec 2021 |
| 208 | Saba Energy Of Texas Inc | Houston, TX 77042 | Oil & Gas Operator | Jul 2007 |
| 209 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 210 | Sanchez-O'Brien | | Oil & Gas Operator | Dec 1984 |
| 211 | Schlaikjer A L | | Oil Operator | Feb 1997 |
| 212 | Seahawk Oil International Inc | Newport Beach, CA 92660 | Oil & Gas Operator | Oct 1997 |
| 213 | Shelco | Maysville, MO 64469 | Oil & Gas Operator | May 2021 |
| 214 | Shenandoah Energy Inc | Denver, CO 80265-1050 | Oil & Gas Operator | Dec 2014 |
| 215 | Sierra Trading Corporation | | Oil & Gas Operator | Sep 1978 |
| 216 | Six Bar Oil LLC | Pine Haven, WY 82721 | Oil & Gas Operator | Feb 2025 |
| 217 | Skinner'S Resources & Expl Inc | | Oil & Gas Operator | Jun 2007 |
| 218 | Skull Creek A LLC | Douglas, WY 82633 | Oil & Gas Operator | Nov 2024 |
| 219 | Skyline Oil Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Jan 1987 |
| 220 | Slaughter J M Oil Company | Fort Worth, TX 76116 | Oil & Gas Operator | Jan 2001 |
| 221 | Snowy Owl LLC | Gillette, WY 82717 | Oil & Gas Operator | Feb 2025 |
| 222 | Sois-Osage Inc | | Oil & Gas Operator | Oct 2006 |
| 223 | South Coast Oil Corporation | Boulder, CO 80302 | Oil & Gas Operator | Oct 2015 |
| 224 | South Pass Petroleum Inc | Casper, WY 82601 | Oil & Gas Operator | Feb 2025 |
| 225 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 226 | Southport Exploration Inc | Tulsa, OK 74103-4015 | Oil & Gas Operator | Nov 1998 |
| 227 | Stewart Petroleum Corporation | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Dec 2023 |
| 228 | Stringer E M | | Oil Operator | May 1996 |
| 229 | Sunshine Valley Petroleum | Casper, WY 82605 | Oil & Gas Operator | Feb 2025 |
| 230 | Surtek Inc | | Oil & Gas Operator | May 1993 |
| 231 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 232 | Teapot Oil & Refining Company | Billings, MT 59101 | Oil & Gas Operator | Mar 2012 |
| 233 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Dec 2024 |
| 234 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 235 | Texas Oil & Gas Corporation | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 236 | Texas Vanguard Oil Company | Austin, TX 78720 | Oil & Gas Operator | Jan 2014 |
| 237 | Thomas Operating Company Inc | Greeley, CO 80634 | Oil & Gas Operator | Aug 2008 |
| 238 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Apr 2025 |
| 239 | Timberline Energy Inc | Franklin, PA 16323-0269 | Oil & Gas Operator | Dec 2023 |
| 240 | Tindall Operating Company | Englewood, CO 80112 | Oil & Gas Operator | Nov 2024 |
| 241 | Toco Corporation | | Oil & Gas Operator | Oct 1991 |
| 242 | Townsend Company | Abilene, TX 79608 | Oil & Gas Operator | Dec 2021 |
| 243 | Transcontinental Oil Corp. | | Oil & Gas Operator | Sep 1985 |
| 244 | Tripower Resources LLC | Ardmore, OK 73402 | Oil & Gas Operator | Apr 2025 |
| 245 | Tripp Oil Company Inc | Houston, TX 77023 | Oil & Gas Operator | Jan 1992 |
| 246 | Trout Kye Jr | | Oil & Gas Operator | Dec 2010 |
| 247 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Feb 2025 |
| 248 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 249 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Feb 2025 |
| 250 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 251 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 252 | Vermilion Energy USA LLC | | Oil & Gas Operator | Feb 2025 |
| 253 | Washakie Oil Company | | Oil & Gas Operator | Dec 1989 |
| 254 | Washburn Lee | Newcastle, WY 82701 | Oil Operator | Jan 2025 |
| 255 | Wave Petroleum Operating LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2025 |
| 256 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Feb 2025 |
| 257 | Western American Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Jun 2024 |
| 258 | Western Gas Resources Inc | Denver, CO 80202-1955 | Oil & Gas Operator | Dec 2007 |
| 259 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 260 | Wichita River Oil Corporation | Englewood, CO 80111 | Oil & Gas Operator | Apr 2009 |
| 261 | Wildfire Partners Inc | Ardmore, OK 73402 | Oil & Gas Operator | Dec 2009 |
| 262 | Williston Basin Cosul-Profit SH | | Oil Operator | Dec 1989 |
| 263 | Winco Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Dec 1997 |
| 264 | Winkler L W & Son | Denver, CO 80222 | Oil & Gas Operator | Dec 2001 |
| 265 | Winter Ridge Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Sep 2011 |
| 266 | Wold Energy Partners LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2022 |
| 267 | WPX Energy Rocky Mountain LLC | Tulsa, OK 74101 | Oil & Gas Operator | Jan 2025 |
| 268 | Wulf Oil Co | | Oil & Gas Operator | Dec 1984 |
| 269 | Wyoming Oil & Minerals Inc | Casper, WY 82601 | Oil & Gas Operator | Jun 2001 |
| 270 | Yegen E C | Casper, WY 82604 | Oil & Gas Operator | Mar 2015 |