| 201 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 202 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Sep 2025 |
| 203 | Oxbow Properties Inc | Centennial, CO 80122-1422 | Oil & Gas Operator | Jan 2025 |
| 204 | Oxtex Inc | | Oil & Gas Operator | Oct 1989 |
| 205 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Jun 2025 |
| 206 | Quicksilver Resources Inc | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2018 |
| 207 | Rainbow Oil Company | | Oil & Gas Operator | Aug 1999 |
| 208 | Ranch Oil Company | West Linn, OR 97068 | Oil & Gas Operator | Jul 2025 |
| 209 | Resolute Wyoming Inc | Denver, CO 80203 | Oil & Gas Operator | May 2018 |
| 210 | Richardson Operating Company | Denver, CO 80237 | Oil & Gas Operator | Jun 2025 |
| 211 | Ridgeland Wyoming Inc | | Oil Operator | Dec 2014 |
| 212 | Robert Hawkins Inc | Kevin, MT 59454 | Oil & Gas Operator | Jul 2025 |
| 213 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2025 |
| 214 | Sage Petroleum LLC | Casper, WY 82601 | Oil Operator | Jun 2008 |
| 215 | Salt Creek West Partners | | Oil Operator | Jul 1995 |
| 216 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 217 | Sauer Bill Oil & Gas Company LLC | Casper, WY 82604 | Oil & Gas Operator | Jun 1999 |
| 218 | Scarlett Energy Enterprises LLC | Watchung, NJ 07069 | Oil & Gas Operator | Oct 2014 |
| 219 | Sharples Phillip T Trust | Denver, CO 80264 | Oil & Gas Operator | Nov 2020 |
| 220 | Skinner Corporation | | Oil Operator | Apr 1985 |
| 221 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | Sep 2025 |
| 222 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Sep 2025 |
| 223 | Smokey Gap Oil Company LLC | | Oil Operator | Jul 2025 |
| 224 | South Pass Petroleum Inc | Casper, WY 82601 | Oil & Gas Operator | Jul 2025 |
| 225 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 226 | Southland Royalty Company LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Jul 2021 |
| 227 | Southwestern Production Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Jul 2025 |
| 228 | Spellbound Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 229 | Stealth Energy Inc | Billings, MT 59101 | Oil Operator | Dec 2011 |
| 230 | Stealth Energy USA Inc | Billings, MT 59104 | Oil Operator | Dec 2017 |
| 231 | Stovall Oil Company | Casper, WY 82602 | Oil & Gas Operator | Aug 1998 |
| 232 | Strachan Exploration Inc | Englewood, CO 80112 | Oil & Gas Operator | Jun 2025 |
| 233 | Summit Resources, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2016 |
| 234 | Sunshine Valley Petroleum | Casper, WY 82605 | Oil & Gas Operator | Jul 2025 |
| 235 | Supron Energy Corp | | Oil & Gas Operator | Oct 1995 |
| 236 | Synergy Offshore LLC | Houston, TX 77024 | Oil & Gas Operator | Feb 2022 |
| 237 | Tbi Exploration Inc | Englewood, CO 801556525 | Oil & Gas Operator | Jun 2011 |
| 238 | Teapot Oil & Refining Company | Billings, MT 59101 | Oil & Gas Operator | Mar 2012 |
| 239 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Jun 2025 |
| 240 | Teocali Energy LLC | Denver, CO 80202 | Oil & Gas Operator | Jul 2025 |
| 241 | Terex Energy Corporation | Casper, WY 82602 | Oil & Gas Operator | Aug 2019 |
| 242 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 243 | Texaco Exploration & Prod | Midland, TX 79702 | Oil & Gas Operator | Aug 2002 |
| 244 | The Brinkerhoff Company | Denver, CO 80202 | Oil & Gas Operator | Dec 2017 |
| 245 | Three Forks Resources LLC | Wheat Ridge, CO 80033 | Oil & Gas Operator | Sep 2025 |
| 246 | Tiger Oil Company | Dallas, TX 75221 | Oil & Gas Operator | May 2007 |
| 247 | Timberline Energy Inc | Franklin, PA 16323-0269 | Oil & Gas Operator | Dec 2024 |
| 248 | Timberline Production Company LLC | Casper, WY 82601 | Oil & Gas Operator | Oct 2020 |
| 249 | Tipps Kenneth L | | Oil & Gas Operator | Jun 2000 |
| 250 | Toc-Rocky Mountain Inc | | Oil & Gas Operator | Oct 2013 |
| 251 | Transglobe Oil & Gas Corporation | Littleton, CO 801222710 | Oil & Gas Operator | Dec 1999 |
| 252 | True Oil LLC | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 253 | Txo Production Corp. | Ganado, TX 77962 | Oil & Gas Operator | Aug 2022 |
| 254 | Tyl Oil | Canon City, CO 81212 | Gas Operator | May 1994 |
| 255 | Tyrex Oil Company | Casper, WY 82602 | Oil & Gas Operator | May 1997 |
| 256 | U V Industries | | Oil & Gas Operator | Jan 1993 |
| 257 | Underwood Oil & Gas | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 258 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 259 | Union Texas Petroleum | Houston, TX 77252 | Oil & Gas Operator | Oct 1991 |
| 260 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Sep 2025 |
| 261 | USA Exploration & Production LLC | Mills, WY 82644 | Oil & Gas Operator | Sep 2012 |
| 262 | V A Resources LLC | Casper, WY 82601 | Oil Operator | Apr 2016 |
| 263 | Vastar Resources Inc | Houston, TX 77253 | Oil & Gas Operator | May 2025 |
| 264 | Vector Minerals Corporation | Aurora, CO 80015 | Oil & Gas Operator | Jun 2025 |
| 265 | Vessels Oil & Gas Company | Denver, CO 80265 | Oil & Gas Operator | Dec 1998 |
| 266 | Viable Resources Inc | Casper, WY 82601 | Oil & Gas Operator | Sep 1989 |
| 267 | Wagner & Brown Limited Partnership | Midland, TX 79701 | Oil & Gas Operator | Feb 2013 |
| 268 | Ware House Industries | Casper, WY 82605 | Oil & Gas Operator | Dec 2013 |
| 269 | Warren Enterprises Inc | Gillette, WY 82718 | Oil Operator | Dec 2022 |
| 270 | Washington Energy Exploration | | Oil & Gas Operator | Dec 1997 |
| 271 | Weaver Oil Inc | | Oil & Gas Operator | Oct 2011 |
| 272 | Wellstar Corporation | Northglenn, CO 80233 | Oil & Gas Operator | Jul 2025 |
| 273 | Wesco Operating, Inc. | Casper, WY 82602 | Oil & Gas Operator | Jul 2025 |
| 274 | Western Gas Resources Inc | Denver, CO 80202 | Oil & Gas Operator | Dec 2004 |
| 275 | Wexpro Company | Rock Springs, WY 82902-0458 | Oil & Gas Operator | Jul 2025 |
| 276 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Sep 2025 |
| 277 | Wold Energy Partners LLC | Denver, CO 80202 | Oil & Gas Operator | Feb 2022 |
| 278 | Wold Oil Properties Inc | Denver, CO 80203 | Oil & Gas Operator | Feb 2018 |
| 279 | WPX Energy Rocky Mountain LLC | Tulsa, OK 74101 | Oil & Gas Operator | Jul 2025 |
| 280 | Yegen E C | Casper, WY 82604 | Oil & Gas Operator | Mar 2015 |