| Larsen, Lewis H | 101257 | — | 1 | 1 |
| Larue, E B Jr | 101258 | Dallas | 7 | 2 |
| Layton Oil & Gas Prod Co | 101260 | Grand Junction | 5 | 1 |
| Lear Petroleum Explor Inc | 101261 | Denver | 5 | 2 |
| Leclair-Westwood Inc | 101262 | Denver | 0 | 0 |
| Legacy Energy Corporation | 101263 | Denver | 2 | 1 |
| Legend Energy Corp | 101264 | Stillwater | 0 | 0 |
| Legend Energy of Utah LLC | 101265 | Glendale | 7 | 1 |
| Legg Resources | 101266 | Grand Junction | 0 | 0 |
| Lehndorff/LGB Minerals Inc | 101267 | Denver | 0 | 0 |
| Lehndorff/LGB Minerals Inc | 101268 | Parker | 0 | 0 |
| Leif Exploration, LLCActive | 105814 | Billings | 41 | 1 |
| Lemm & Maiatico | 101269 | — | 2 | 2 |
| Leonard Petroleum Co | 101270 | — | 2 | 1 |
| Leonora Mining & Milling | 101271 | — | 2 | 1 |
| Liberty Oil & Gas Corp | 101275 | New Roads | 2 | 1 |
| Liberty Petroleum Corp | 101276 | Phoenix | 1 | 1 |
| Liberty Pioneer Energy Source, Inc | 101277 | Provo | 23 | 5 |
| Linmar Energy Corporation | 101278 | Denver | 14 | 2 |
| Linmar Petroleum Company | 101279 | Denver | 16 | 1 |
| Linmar Petroleum Company | 101280 | Denver | 3 | 1 |
| Linn Bros Oil & Gas IncActive | 101281 | Fruita | 11 | 1 |
| Linn Operating Inc | 101282 | Houston | 0 | 0 |
| Linn Operating Inc | 101283 | Houston | 0 | 0 |
| Linn Operating LLC | 101284 | Houston | 4 | 1 |
| Lion Oil Company | 101285 | — | 5 | 4 |
| Lion Oil Company LLC | 101286 | Denver | 0 | 0 |
| Little, Curtis J | 101287 | Albuquerque | 1 | 1 |
| Lockhart, L M | 101289 | — | 1 | 1 |
| Lockridge, John P | 101290 | Denver | 12 | 2 |
| Lodestone Operating, Inc | 101291 | Portland | 1 | 1 |
| Loma Energy Corporation | 101292 | Billings | 0 | 0 |
| Lomak Operating Company | 101293 | Ft Worth | 0 | 0 |
| Lomax Exploration Company | 101294 | Roosevelt | 114 | 2 |
| London San Juan Oil Co | 101295 | — | 3 | 1 |
| Lone Mtn Production Co | 101296 | Billings | 44 | 2 |
| Lone Star Production Co | 101297 | Midland | 1 | 1 |
| Lonewolf E&P Company | 101298 | Billings | 0 | 0 |
| Long Canyon | 101299 | — | 0 | 0 |
| Long, Bob & Howell | 101300 | — | 1 | 1 |
| Longhorn Geoscience | 104123 | Sugar Land | 0 | 0 |
| Longwall Petroleum Co | 101301 | — | 1 | 1 |
| Losey, Carl | 101302 | — | 5 | 1 |
| Louis Dreyfus Nat Gas Corp | 101303 | Oklahoma City | 0 | 0 |
| Louisiana Land & Explor Co | 101304 | Denver | 3 | 3 |
| Lovell, Dwayne B | 101305 | — | 2 | 1 |
| LT Land Group, LLC | 105129 | Bountiful | 0 | 0 |
| Luff Exploration Company | 101306 | Denver | 23 | 2 |
| Lyon, Joe Jr | 101308 | — | 8 | 1 |
| M M Douglas Petroleum Co | 101309 | — | 1 | 1 |
| Mac Donald Oil | 101310 | Midland | 1 | 1 |
| Mac Fulton Drilling Co | 101311 | — | 1 | 1 |
| Mac Petroleum | 101312 | — | 0 | 0 |
| Macpet | 101313 | Denver | 1 | 1 |
| Maddox, Robert L | 101314 | — | 1 | 1 |
| Magnum Drl Services Inc | 101315 | Minden | 0 | 0 |
| Magnum Holdings, LLC | 104437 | — | 0 | 0 |
| Magnum Ngls Solution Mining LLC | 101316 | Holladay | 0 | 0 |
| Magnum Solution Mining LLC | 101317 | Holladay | 1 | 1 |
| Main, W S L | 101318 | — | 0 | 0 |
| Mainard, Richard | 101319 | Blanding | 1 | 1 |
| Major Uranium & Drilling | 101320 | — | 0 | 0 |
| Mak-J Energy Partners LTD | 101321 | Denver | 0 | 0 |
| Mandrake Lithium USA, Inc.Active | 105401 | Midvale | 3 | 1 |
| Mangels, C H | 101322 | — | 1 | 1 |
| Mapco Inc | 101323 | Billings | 3 | 2 |
| Mapco Oil & Gas Company | 101324 | Tulsa | 5 | 2 |
| Mapco Production Co | 101325 | Billings | 29 | 1 |
| Mapp Exploration | 101326 | Houston | 3 | 1 |
| Mar/Reg Oil CompanyActive | 101327 | Reno | 13 | 1 |
| Maralex Resources Inc | 101328 | Ignacio | 0 | 0 |
| Maralo LLC | 101329 | Midland | 1 | 1 |
| Marathon Ashland Petro LLC | 101330 | Findlay | 0 | 0 |
| Marathon Oil Company | 101331 | Tulsa | 45 | 11 |
| Marathon Oil Company | 101332 | Findlay | 0 | 0 |
| Marathon Oil Company | 101333 | Cody | 0 | 0 |
| Marathon Petroleum Supply and Trade, LLC | 105112 | Findlay | 0 | 0 |
| Marion Energy Inc | 101334 | Houston | 0 | 0 |
| Marion Energy Inc | 101335 | Houston | 25 | 1 |
| Marion/Bayless | 101336 | — | 0 | 0 |
| Marks, T Keith | 101337 | Denver | 0 | 0 |
| Marland Oil Co | 101338 | — | 1 | 1 |
| Marshall, Leon | 101339 | — | 1 | 1 |
| Martin, George | 101340 | — | 2 | 1 |
| Master Pet & Devel Co Inc | 101342 | Grand Junction | 8 | 1 |
| Master Pet & Devel Co Inc | 101343 | Salt Lake City | 0 | 0 |
| Matrix Production CompanyActive | 101344 | Sugar Land | 3 | 1 |
| Maude Ellen Oil Co | 101345 | — | 1 | 1 |
| Maverick Operating, LLC | 105068 | Salt Lake City | 1 | 1 |
| Maximum Energy Corporation | 101346 | Roosevelt | 0 | 0 |
| Maxus Exploration Co | 101347 | Dallas | 9 | 2 |
| May Petroleum Inc | 101348 | — | 5 | 4 |
| Mayers & Company | 101349 | Englewood | 0 | 0 |
| Mayhew, E J | 101350 | — | 1 | 1 |
| Mayo-Utah Oil Co | 101351 | — | 1 | 1 |
| MC & MC Disposal | 101353 | Roosevelt | 0 | 0 |
| Mc Alester Fuel Co | 101354 | Magnolia | 1 | 1 |
| Mc Bride, W C | 101355 | — | 4 | 1 |
| Mc Callister Fuel | 101356 | Magnolia | 0 | 0 |
| Mc Carthy Oil Company | 101357 | Elko | 1 | 1 |
| Mc Cullough Oil & Gas | 101358 | Oklahoma City | 7 | 1 |
| Mc Kim, Harry | 101359 | — | 1 | 1 |
| McAdams, J F | 101360 | — | 6 | 4 |
| McCollum, Jack M | 101361 | Denver | 1 | 1 |
| McConnell, B L Operating | 101362 | Fruita | 1 | 1 |
| McCulliss Resources Co Inc | 101363 | Littleton | 1 | 1 |
| McCulloch Geothermal Corporation | 101364 | — | 1 | 1 |
| McCulloch Oil Corp of CA | 101365 | — | 11 | 2 |
| McDermott, J R | 101366 | — | 3 | 1 |
| McDonald, G W | 101367 | Tyler | 0 | 0 |
| McElroy, E R | 101368 | — | 1 | 1 |
| McElvain Energy Inc | 101369 | Denver | 2 | 1 |
| McElvain Oil & Gas Properties Inc | 101370 | Denver | 19 | 1 |
| McKennon Drilling & Devel | 101371 | — | 1 | 1 |
| McKensey, D C | 101372 | — | 1 | 1 |
| McKenzie Petroleum Company | 101373 | Houston | 1 | 1 |
| McKenzie Petroleum Company | 101374 | Roosevelt | 0 | 0 |
| McKenzie Petroleum Company | 101375 | Denver | 0 | 0 |
| McKenzie Production Co | 101376 | Houston | 0 | 0 |
| McKinnon, Malcolm N | 101377 | — | 2 | 2 |
| McLish & Luff | 101378 | Denver | 4 | 1 |
| McLish, Holmes P | 101379 | Denver | 1 | 1 |
| McMillan & Associates | 101380 | Salt Lake City | 1 | 1 |
| McMillin & Johnson Oil | 101381 | — | 6 | 1 |
| McMoran-Freeport Oil & Gas | 101382 | Denver | 1 | 1 |
| McMullin, G S | 101383 | — | 1 | 1 |
| McMurry Oil Company | 101384 | Casper | 2 | 1 |
| McNeely, Luther | 101385 | Lubbock | 1 | 1 |
| Mco Resources Inc | 101386 | — | 0 | 0 |
| Mcor Oil & Gas Corp | 101387 | Houston | 16 | 1 |
| McRae & Henry LTD | 101388 | Denver | 0 | 0 |
| McRae Oil & Gas Corp | 101389 | — | 1 | 1 |
| Medallion Exploration | 101390 | Holladay | 43 | 3 |
| Medallion Production Co | 101391 | Tulsa | 0 | 0 |
| Meek, Chad/P&M Petroleum | 101392 | Denver | 1 | 1 |
| Megadon Energy Corp | 101393 | — | 1 | 1 |
| Megadon Enterprises, Inc | 101394 | Salt Lake City | 17 | 3 |
| Menor, J E & Aubrey, Geo | 101395 | — | 1 | 1 |
| Mercuria Energy Trading Inc | 101397 | Houston | 0 | 0 |
| Meridian Oil Inc | 101398 | Englewood | 20 | 1 |
| Meridian Oil Trading Inc | 101399 | Ft Worth | 0 | 0 |
| Merit Energy Company | 101401 | Dallas | 11 | 3 |
| Merrion & Bayless | 101402 | Farmington | 5 | 1 |
| Merrion Oil & Gas Corp | 101404 | Farmington | 16 | 2 |
| Merron & Julander | 101403 | — | 1 | 1 |
| Mesa Oper LTD Partnership | 101405 | Amarillo | 0 | 0 |
| Mesa Operating Co | 101406 | Amarillo | 0 | 0 |
| Mesa Pipeline | 101408 | Denver | 0 | 0 |
| Mesa Production Company | 101407 | Amarillo | 2 | 1 |
| Mexican Hat Oil | 101409 | Farmington | 2 | 1 |
| Mezo, J D | 101410 | Grand Junction | 5 | 1 |
| Mgm Petroleum Inc | 101411 | — | 1 | 1 |
| Miami Oil Producers Inc | 101412 | — | 8 | 2 |
| Mich-Wisc Pipeline Company | 101413 | Denver | 1 | 1 |
| Mid-American Oil | 101415 | — | 1 | 1 |
| Mid-Central Oil & Minerals | 101416 | — | 1 | 1 |
| Mid-Continent Oil & Gas | 101417 | Dallas | 2 | 1 |
| Mid-Continent Petro Corp | 101418 | — | 1 | 1 |
| Mid-Power Resource Corp | 101419 | Las Vegas | 1 | 1 |
| Middle Fork Energy Uinta, LLC | 104506 | Denver | 0 | 0 |
| Midway Oil & Refining Co | 101422 | — | 2 | 2 |
| Midway Petroleum Co | 101423 | — | 1 | 1 |
| Midwest & Utah Southern Oil | 101424 | — | 1 | 1 |
| Midwest Exploration Co | 101425 | — | 6 | 3 |
| Midwest Oil Corporation | 101426 | Denver | 2 | 1 |
| Milagro Energy Resources | 101427 | — | 3 | 1 |
| Milestone Pet/El Paso Expl | 101428 | — | 1 | 1 |
| Milestone Petroleum Inc | 101429 | — | 1 | 1 |
| Miller & Taylor | 101430 | — | 1 | 1 |
| Miller Dyer Res LLC | 101431 | Denver | 0 | 0 |
| Miller Energy Inc | 101432 | Portage | 2 | 1 |
| Miller, Dyer & Co LLC | 101433 | Denver | 14 | 2 |
| Miller, Helene H | 101434 | — | 1 | 1 |
| Miller, Hickey & Lambert | 101435 | — | 1 | 1 |
| Miller-Christensen Oil | 101436 | Casper | 0 | 0 |
| Mineral Hill Uranium | 101438 | — | 1 | 1 |
| Minerals Management Inc | 101439 | — | 2 | 2 |
| Minton, Joseph A | 101440 | — | 3 | 1 |
| Miracle & Wooster Drilling | 101441 | — | 1 | 1 |
| Miracle Rock Mining and Research LLC | 101442 | Emery | 0 | 0 |
| Mission Energy LLC | 101443 | Encinitas | 1 | 1 |
| Mission Oil Corporation | 101444 | Ft Collins | 0 | 0 |
| Mitchell Energy Co LP | 101445 | The Woodlands | 0 | 0 |
| Mitchell Energy Corp | 101446 | The Woodlands | 6 | 1 |
| Mitchell Pit (Oily Waste) | 101447 | Altamont | 0 | 0 |
| Moab Drilling Co Inc | 101448 | — | 1 | 1 |
| Moab Oil Co | 101449 | — | 3 | 2 |
| Mobil E&P North America | 101450 | — | 0 | 0 |
| Mobil E&P North America | 101451 | Dallas | 0 | 0 |
| Mobil Explor & Prod | 101452 | Cortez | 87 | 1 |
| Mobil Oil Corporation | 101453 | Dallas | 21 | 9 |
| Modern Minerals Corp | 101454 | — | 2 | 1 |
| Mohawk Petroleum Co | 101455 | — | 2 | 2 |
| Monahan, Rex | 101456 | Sterling | 2 | 1 |
| Monarch Midstream LLC | 105473 | Greenwood Village | 0 | 0 |
| Monarch Natural Gas, LLC | 101457 | Greenwood Village | 0 | 0 |
| Monarch Natural Gas, LLC | 101458 | Greenwood Village | 0 | 0 |
| Moncrief and Champlin Petr | 101459 | Casper | 1 | 1 |
| Moncrief Oil | 101460 | Casper | 9 | 2 |
| Mono Power | 101461 | Rosemead | 0 | 0 |