| 301 | NP Resources, LLC | | Oil & Gas Operator | Aug 2022 |
| 302 | Nucorp Energy, Inc. | | Oil & Gas Operator | Jan 1985 |
| 303 | Oasis Petroleum North America LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 304 | Omimex International Corp | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Feb 2025 |
| 305 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 306 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 307 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 308 | Ovaco Energy Inc. | | Oil & Gas Operator | Nov 2009 |
| 309 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 310 | Oxy Little Knife, LLC | | Oil & Gas Operator | Jan 2016 |
| 311 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2025 |
| 312 | P.O.&G. Operating, LLC | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 313 | Pacific Enterprises Oil Co USA | Dallas, TX 75201 | Oil & Gas Operator | Feb 2001 |
| 314 | Pan American Petroleum Corp | | Oil & Gas Operator | Jan 2008 |
| 315 | Panamerican Operating Inc | Dallas, TX 75219 | Oil & Gas Operator | May 2025 |
| 316 | Panther Creek Resources, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2012 |
| 317 | Panther Energy Company, LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2022 |
| 318 | Patrick Petroleum Co. | Jackson, MI 49201 | Oil & Gas Operator | Nov 1993 |
| 319 | Paul Rankin Inc. | | Oil & Gas Operator | Mar 2025 |
| 320 | PDC Corporation | | Oil & Gas Operator | Jan 2011 |
| 321 | Penn VIrginia Oil & Gas, L.P. | Houston, TX 77084 | Oil & Gas Operator | Nov 2022 |
| 322 | Pennzoil Exploration & Production Co. | Carthage, TX 75633 | Oil & Gas Operator | Mar 2008 |
| 323 | Peregrine Petroleum Partners, LTD | | Oil & Gas Operator | Oct 2021 |
| 324 | Petro Harvester Operating Company, LLC | | Oil & Gas Operator | Nov 2022 |
| 325 | Petro-Hunt Dakota, LLC | | Oil & Gas Operator | Mar 2025 |
| 326 | Petro-Hunt, L.L.C. | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 327 | Petrogulf Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 328 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 329 | Petrosearch Operating Co, LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 330 | Petroshale (Us) Inc. | | Oil & Gas Operator | Mar 2025 |
| 331 | Phillip D. Armstrong | | Oil & Gas Operator | Sep 2018 |
| 332 | Phillips & Ralph M. Ballard | | Oil Operator | Jan 1960 |
| 333 | Phillips Petroleum Company | Houston, TX 77251 | Oil & Gas Operator | Mar 2013 |
| 334 | Phoenix Operating LLC | Denver, CO 80237 | Oil & Gas Operator | Mar 2025 |
| 335 | Phoenix Petroleum, LLC | | Oil & Gas Operator | Mar 2025 |
| 336 | Pintail Petroleum Inc. | Wichita, KS 67202 | Oil & Gas Operator | Jun 2010 |
| 337 | Pintail Petroleum, LTD. | Wichita, KS 67202 | Oil & Gas Operator | Apr 2021 |
| 338 | Pogo Producing Company | Houston, TX 77002 | Oil & Gas Operator | Jan 2008 |
| 339 | Pogo Producing Company LLC | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 340 | Prairie Production, Inc. | | Oil & Gas Operator | Apr 2020 |
| 341 | Prenalta Corporation | Terrytown, NY 10591 | Oil & Gas Operator | Jan 1997 |
| 342 | Presidio Exploration, Inc. | Englewood, CO 80155 | Oil & Gas Operator | May 1999 |
| 343 | Pride Energy, An Oklahoma General Partnership | | Oil & Gas Operator | Dec 2020 |
| 344 | Prima Exploration, Inc. | Denver, CO 80206 | Oil & Gas Operator | Apr 2025 |
| 345 | Primewest Petroleum Inc. | Centennial, CO 80111 | Oil & Gas Operator | Jan 2009 |
| 346 | Prospective Investment & Trading Co., LTD., The | Tulsa, OK 74170-2320 | Oil & Gas Operator | Apr 2014 |
| 347 | Prosper Energy Corporation | | Oil & Gas Operator | Oct 1988 |
| 348 | Proven Petroleum, Inc. | Lakewood, CO 80228 | Oil & Gas Operator | Mar 2025 |
| 349 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Feb 2025 |
| 350 | Questar Expl. And Prod. Co. | Salt Lake Cty, UT 84145 | Oil & Gas Operator | Jul 2011 |
| 351 | Ragnar Exploration, LLC | | Oil & Gas Operator | Mar 2025 |
| 352 | Rainbow Resources, Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Aug 2007 |
| 353 | Ranch Oil Company | West Linn, OR 97068 | Oil & Gas Operator | Apr 2025 |
| 354 | RDT Properties, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Oct 2012 |
| 355 | Remuda Energy Development LLC | Billings, MT 59104 | Oil & Gas Operator | Mar 2025 |
| 356 | Resolute Natural Resources Co., LLC | Denver, CO 80203 | Oil & Gas Operator | Feb 2017 |
| 357 | Resonance Exploration (North Dakota) LLC | | Oil & Gas Operator | Apr 2025 |
| 358 | Resource Energy Can-Am LLC | | Oil & Gas Operator | May 2022 |
| 359 | Rigel, Inc. | | Oil & Gas Operator | Feb 2010 |
| 360 | Rim Operating, Inc. | Englewood, CO 80112 | Oil & Gas Operator | May 2025 |
| 361 | Ritchie Exploration, Inc. | Wichita, KS 67278 | Oil & Gas Operator | Feb 2025 |
| 362 | Ritter, Laber & Associates, Inc. | Williston, ND 58802 | Oil & Gas Operator | Oct 2024 |
| 363 | Rocanville Corporation | Dallas, TX 75225 | Oil & Gas Operator | Dec 2016 |
| 364 | Rockport Energy Solutions LLC | Austin, TX 78730 | Oil & Gas Operator | May 2025 |
| 365 | Rocky Top Energy LLC | Bartlesville, OK 74003 | Oil & Gas Operator | Sep 2024 |
| 366 | Ronald M. Sannes | | Oil & Gas Operator | Oct 2016 |
| 367 | Ryan Exploration, Inc. | | Oil & Gas Operator | Mar 2012 |
| 368 | Sage Energy Company | San Antonio, TX 78215 | Oil & Gas Operator | May 2025 |
| 369 | Sagebrush Resources, LLC | | Oil & Gas Operator | Jan 2011 |
| 370 | Samedan Oil Corporation | Houston, TX 77067 | Oil & Gas Operator | Dec 2019 |
| 371 | Samson Oil & Gas USA Inc | Denver, CO 80202 | Oil & Gas Operator | Mar 2025 |
| 372 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Feb 2025 |
| 373 | Samuel Gary Jr. & Associates, Inc. | Denver, CO 80202 | Oil & Gas Operator | Jan 2025 |
| 374 | Santa Fe Energy Company | Midland, TX 79701 | Oil & Gas Operator | Dec 2015 |
| 375 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | May 2025 |
| 376 | Sedalia Energy, LLC | | Oil & Gas Operator | Mar 2018 |
| 377 | Sequel Energy, LLC | | Oil & Gas Operator | May 2014 |
| 378 | Shakespeare Oil Co Inc | Salem, IL 62881 | Oil & Gas Operator | Mar 2025 |
| 379 | Shell Oil Company | Houston, TX 77210 | Oil & Gas Operator | Apr 2015 |
| 380 | Shell Western E&P | Houston, TX 77001 | Oil & Gas Operator | May 2025 |
| 381 | Siana Oil & Gas., L.L.C | | Oil & Gas Operator | Dec 2021 |
| 382 | Silver Hill Energy Operating, LLC | Dallas, TX 75201 | Oil & Gas Operator | May 2025 |
| 383 | Silver Oak Energy, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2016 |
| 384 | Silver Thread Oil & Gas, Inc. | | Oil & Gas Operator | Jul 2015 |
| 385 | Simray GP, LLC | Richardson, TX 75080 | Oil & Gas Operator | Dec 2015 |
| 386 | Sinclair Oil & Gas Company | Salt Lake Cty, UT 84130 | Oil & Gas Operator | May 2025 |
| 387 | Sinclair Oil Corporation | Salt Lake Cty, UT 84130 | Oil & Gas Operator | Aug 2006 |
| 388 | Skelly Oil Co | | Oil & Gas Operator | Mar 2005 |
| 389 | Slawson Exploration Company Inc | Oklahoma City, OK 73102 | Oil & Gas Operator | May 2025 |
| 390 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | May 2025 |
| 391 | Sogc, Inc. | Salt Lake Cty, UT 84131 | Oil & Gas Operator | Mar 2025 |
| 392 | Sohio Petroleum Co. | Casper, WY 82602 | Oil & Gas Operator | Apr 1986 |
| 393 | South Heart Company | | Oil Operator | Aug 2010 |
| 394 | South Oak Production Company | | Oil & Gas Operator | Jun 2010 |
| 395 | Southern Union Exploration Co. | Austin, TX 78701 | Oil & Gas Operator | Feb 2002 |
| 396 | Southern Union Production Co. | | Oil Operator | Apr 1979 |
| 397 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 398 | Southwestern Production Corporation | Lakewood, CO 80228 | Oil & Gas Operator | Mar 2025 |
| 399 | Sparrow Oil & Gas LLC | | Oil & Gas Operator | Apr 2025 |
| 400 | Specialized Technological Threading, Inc., | | Oil & Gas Operator | Oct 2019 |