| 301 | L B Industries Inc | Englewood, CO 80112 | Oil & Gas Operator | Jun 2003 |
| 302 | Lacy, R | Longview, TX 75606 | Oil Operator | Apr 1989 |
| 303 | Ladd Petroleum Corp. | Denver, CO 80202 | Oil & Gas Operator | Oct 2004 |
| 304 | Liberty Pioneer Energy Source, Inc | Provo, UT 84604 | Oil & Gas Operator | Oct 2021 |
| 305 | Linmar Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Oct 1987 |
| 306 | Linmar Petroleum Company | Denver, CO 80237 | Oil & Gas Operator | Oct 1995 |
| 307 | Linn Bros Oil & Gas Inc | Fruita, CO 81521 | Oil & Gas Operator | Mar 2026 |
| 308 | Linn Operating, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2017 |
| 309 | Linn Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Jan 2019 |
| 310 | Lockridge, John P | Denver, CO 80202 | Gas Operator | Mar 1999 |
| 311 | Lodestone Operating, Inc. | Portland, TX 78374 | Oil & Gas Operator | May 2026 |
| 312 | Lomax Exploration Company | Roosevelt, UT 84066 | Oil & Gas Operator | Jun 1995 |
| 313 | Lone MTN Production Co | Billings, MT 59108-0965 | Oil & Gas Operator | Jul 2019 |
| 314 | Luff Exploration Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2026 |
| 315 | Mapco Inc | Billings, MT 59102 | Oil & Gas Operator | Dec 1983 |
| 316 | Mapco Oil & Gas Company | Tulsa, OK 74101-2115 | Oil & Gas Operator | Jan 1985 |
| 317 | Mapco Production Co | Billings, MT 59102 | Oil & Gas Operator | Apr 1994 |
| 318 | Mar/Reg Oil Company | Reno, NV 89511 | Oil & Gas Operator | Mar 2026 |
| 319 | Maralex Resources Inc | Ignacio, CO 81137 | Oil & Gas Operator | Mar 2026 |
| 320 | Marathon Oil Company | Houston, TX 77252 | Oil & Gas Operator | Mar 2026 |
| 321 | Marion Energy Inc | Houston, TX 770082292 | Oil & Gas Operator | May 2015 |
| 322 | Matrix Production Company | Sugar Land, TX 77478 | Oil & Gas Operator | Mar 2026 |
| 323 | Maxus Exploration Company | Dallas, TX 75201 | Oil & Gas Operator | Jan 1995 |
| 324 | McAdams, J F | | Oil Operator | May 1971 |
| 325 | McCulliss Resources Co Inc | Littleton, CO 80161-3248 | Oil & Gas Operator | Jun 2009 |
| 326 | McCulloch Geothermal Corporation | | Oil & Gas Operator | Jun 1982 |
| 327 | McCulloch Oil Corp Of Ca | | Oil & Gas Operator | May 1980 |
| 328 | McElvain Energy Inc | Denver, CO 80265 | Oil & Gas Operator | Nov 2019 |
| 329 | McElvain Oil & Gas Properties Inc | Denver, CO 80265-2080 | Oil & Gas Operator | Jul 2011 |
| 330 | McKenzie Petroleum Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 331 | McKenzie Production Company | Houston, TX 77063 | Oil & Gas Operator | May 1995 |
| 332 | McLish, Holmes P | Denver, CO 80202 | Oil & Gas Operator | Dec 1983 |
| 333 | McOr Oil & Gas Corp | Houston, TX 77002 | Oil & Gas Operator | Oct 2013 |
| 334 | McRae & Henry LTD | Golden, CO 80401 | Oil & Gas Operator | May 2022 |
| 335 | Medallion Exploration | Holladay, UT 84117 | Oil & Gas Operator | Dec 2015 |
| 336 | Medallion Production Company | Tulsa, OK 74103 | Oil & Gas Operator | May 1997 |
| 337 | Megadon Enterprises, Inc | Salt Lake City, UT 84121 | Oil Operator | May 2020 |
| 338 | Meridian Oil Inc. | Houston, TX 77210 | Oil & Gas Operator | Aug 1996 |
| 339 | Merit Energy Company | Dallas, TX 75240 | Oil & Gas Operator | May 2026 |
| 340 | Merrion & Bayless | Farmington, NM 87401 | Oil & Gas Operator | May 1982 |
| 341 | Merrion Oil & Gas Corp | Farmington, NM 87401 | Oil & Gas Operator | Mar 2026 |
| 342 | Mesa Operating LTD Partnership | Amarillo, TX 79189 | Oil & Gas Operator | May 1994 |
| 343 | Mesa Production Company | Amarillo, TX 79189 | Oil & Gas Operator | Dec 1983 |
| 344 | Miami Oil Producers Inc | Reno, NV 89501 | Oil & Gas Operator | Dec 2012 |
| 345 | Milestone Pet/El Paso Expl | | Oil & Gas Operator | Jul 1985 |
| 346 | Miller Energy Inc | Houston, TX 77024 | Oil & Gas Operator | Oct 2016 |
| 347 | Miller, Dyer & Co LLC | Denver, CO 80202 | Oil & Gas Operator | May 2009 |
| 348 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |
| 349 | Mobil Explor & Prod | Cortez, CO 81321 | Oil & Gas Operator | May 2001 |
| 350 | Mobil Oil Corporation | Houston, TX 77210 | Oil & Gas Operator | Dec 2007 |
| 351 | Monahan Rex | Sterling, CO 80751 | Oil & Gas Operator | Jun 2002 |
| 352 | Moncrief Oil | Casper, WY 82602 | Oil & Gas Operator | Feb 1986 |
| 353 | Monsanto | Englewood, CO 80111 | Oil & Gas Operator | Apr 1986 |
| 354 | Moose Mountain Divide #1, LLC | Roosevelt, UT 84066-1656 | Oil & Gas Operator | Mar 2026 |
| 355 | Mountain Fuel Supply Co | Salt Lake City, UT 84139 | Oil & Gas Operator | May 1984 |
| 356 | Mountain Oil And Gas Inc | Roosevelt, UT 84066 | Oil & Gas Operator | Feb 2026 |
| 357 | Mountain Petroleum Corp | Denver, CO 80202 | Oil & Gas Operator | Apr 2013 |
| 358 | Mountain Resource Corporation | Salt Lake City, UT 84124 | Oil & Gas Operator | Dec 1988 |
| 359 | Mountain States Petroleum Corp | Midland, TX 79702 | Oil & Gas Operator | Apr 2008 |
| 360 | Murdoch Oil Co Inc | Bluff, UT 84512 | Oil & Gas Operator | Jun 2010 |
| 361 | Mustang Fuel Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2026 |
| 362 | Nacogdoches Oil & Gas Inc | Nacogdoches, TX 75963 | Oil & Gas Operator | May 2026 |
| 363 | Nadk, LLC | Orem, UT 84097 | Oil & Gas Operator | Apr 2026 |
| 364 | National Oil Company | Garden City, KS 67846 | Oil & Gas Operator | Jun 2024 |
| 365 | Natural Gas Corp Of Ca | Vernal, UT 84078 | Oil & Gas Operator | Jun 1989 |
| 366 | Navajo Nation Oil & Gas Co | Window Rock, AZ 86511 | Oil & Gas Operator | Oct 2012 |
| 367 | Newfield Production Company | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Jul 2022 |
| 368 | Nicor Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Jun 1993 |
| 369 | Nnogc Exploration & Production, LLC | Window Rock, AZ 86515 | Oil & Gas Operator | Mar 2026 |
| 370 | Noble Energy Inc | Midland, TX 79706 | Oil & Gas Operator | May 2026 |
| 371 | North Plains Corp | Tulsa, OK 74137 | Oil & Gas Operator | Jan 2026 |
| 372 | North Shore Exploration & Prod LLC | Broomfield, CO 80021 | Oil & Gas Operator | Mar 2026 |
| 373 | Northstar Gas Company Of Texas | Houston, TX 77057-2768 | Oil & Gas Operator | Jan 2026 |
| 374 | Northstar Gas, Inc. | Orem, UT 84097-6360 | Oil & Gas Operator | Mar 2026 |
| 375 | Northwest Exploration Co | Salt Lake City, UT 84108-0900 | Oil & Gas Operator | Sep 1991 |
| 376 | Nova Natural Res Corp | Denver, CO 80202 | Oil & Gas Operator | Nov 1989 |
| 377 | Nova Petroleum Corp | Salt Lake City, UT 84147 | Oil & Gas Operator | Sep 1986 |
| 378 | NP Energy Corporation | Englewood, CO 80111 | Oil & Gas Operator | Jun 1989 |
| 379 | Ocean Energy Inc | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 380 | Odegard Resources/Omni Exp | Columbus, OH 43207 | Oil & Gas Operator | Sep 1986 |
| 381 | Oil Development Co | | Oil & Gas Operator | Jan 1979 |
| 382 | Oil Inc | | Oil & Gas Operator | Dec 1971 |
| 383 | Olympic Exploration Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2004 |
| 384 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 385 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | Mar 2026 |
| 386 | Oso Oil & Gas Properties LLC | Price, UT 84501 | Gas Operator | Jun 2016 |
| 387 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | May 2026 |
| 388 | Oxbow Properties Inc | Centennial, CO 80122-1422 | Oil & Gas Operator | Jan 2025 |
| 389 | P & M Petroleum Management | Denver, CO BAD ADDR | Oil & Gas Operator | Apr 2010 |
| 390 | P-2 Oil | Vernal, UT 84078 | Oil & Gas Operator | Jul 2000 |
| 391 | Pacific Energy & Mining Company | Reno, NV 89511 | Oil & Gas Operator | Sep 2022 |
| 392 | Pacific Natural Gas Explor | | Oil & Gas Operator | Dec 1974 |
| 393 | Pacific Trans Supply | Vernal, UT 84078 | Oil & Gas Operator | Jul 1987 |
| 394 | Page Petroleum Inc | Calgary, AB T2P3M-3000 | Oil & Gas Operator | Nov 1998 |
| 395 | Paiute Oil & Mining Corp | Salt Lake City, UT 84117 | Oil & Gas Operator | Jun 1989 |
| 396 | Pan American Petroleum Cor | | Oil & Gas Operator | Dec 1981 |
| 397 | Pannonian Energy Inc | Englewood, CO 80112 | Oil & Gas Operator | Mar 2004 |
| 398 | Paradox Upstream, LLC | Houston, TX 77002 | Oil & Gas Operator | Apr 2025 |
| 399 | Parker Energy Tech Inc | Salt Lake City, UT 84171 | Oil Operator | Nov 2013 |
| 400 | Patara Oil & Gas LLC | Dallas, TX 75219 | Oil & Gas Operator | Mar 2018 |