| 301 | O'Brien Resources LLC | Shreveport, LA 71136 | Oil Operator | Nov 2017 |
| 302 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 303 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 304 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 305 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Aug 2025 |
| 306 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 307 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 308 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Sep 2025 |
| 309 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 310 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 311 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 312 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 313 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 314 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Sep 2025 |
| 315 | Outback Petroleum Inc | Moore, OK 73160-9998 | Oil & Gas Operator | Mar 2015 |
| 316 | Ovation Energy II, LP | Houston, TX 77279 | Oil & Gas Operator | Jun 2011 |
| 317 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |
| 318 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Dec 2025 |
| 319 | Pacific Enterprise Oil Co USA | Los Angeles, CA 90071-2005 | Oil & Gas Operator | Aug 2012 |
| 320 | Pacific Enterprises Royalty Co | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 321 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2025 |
| 322 | Paluca Petroleum Inc | Holdenville, OK 74848 | Oil & Gas Operator | Aug 2025 |
| 323 | Panenergy Services Inc | Houston, TX 77525 | Oil & Gas Operator | May 2001 |
| 324 | Panexco Operating LLC | Oklahoma City, OK 73103-2203 | Oil & Gas Operator | Oct 2014 |
| 325 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 326 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 327 | Payne W C Family Trust | Oklahoma City, OK 73116-9044 | Oil & Gas Operator | Mar 2015 |
| 328 | Pegasus Energy Corporation | Oklahoma City, OK 73162 | Oil & Gas Operator | Mar 2015 |
| 329 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Sep 2025 |
| 330 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 331 | Petrocorp Incorporated | Tulsa, OK 74170 | Oil & Gas Operator | Nov 2021 |
| 332 | Petroleum Inc | Wichita, KS 67202 | Oil & Gas Operator | Oct 2021 |
| 333 | Petroleum Production MGMT., Inc. | Kansas City, MO 64112 | Oil & Gas Operator | Dec 2025 |
| 334 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 335 | Petroleum Reserve Corporation | Plymouth MTNG, PA 19462 | Oil & Gas Operator | May 2008 |
| 336 | Pheldon Oil Production Inc | Asher, OK 74826-2629 | Oil & Gas Operator | Dec 2024 |
| 337 | Pioneer Exploration Company | Houston, TX 77090 | Oil & Gas Operator | Sep 2025 |
| 338 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Dec 2025 |
| 339 | Pogue Randall | Ada, OK 74821-1547 | Oil & Gas Operator | Apr 2014 |
| 340 | Post Petroleum Company | Oklahoma City, OK 73116 | Oil & Gas Operator | Aug 2013 |
| 341 | Pride Energy Company | Tulsa, OK 74170 | Oil & Gas Operator | Dec 2025 |
| 342 | Primary Natural Resources III LLC | Tulsa, OK 74136-6351 | Oil & Gas Operator | Sep 2025 |
| 343 | Prime Energy Corp | Charleston, WV 25301-1707 | Oil & Gas Operator | Sep 2015 |
| 344 | Prime Operating Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 345 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 346 | Prospective Investment & Trading | Scottsdale, AZ 85261-4190 | Oil & Gas Operator | Jun 2016 |
| 347 | Protege Energy LLC | Tulsa, OK 74135 | Oil & Gas Operator | Jan 2018 |
| 348 | Proven Reserves Management, Inc. | Dallas, TX 75370 | Oil & Gas Operator | Aug 2025 |
| 349 | Psec Inc | Tulsa, OK 74102-0871 | Oil & Gas Operator | Dec 2016 |
| 350 | Pybas Robert | Wanette, OK 74878 | Oil Operator | Apr 2014 |
| 351 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Aug 2025 |
| 352 | Quest Property Inc | Yukon, OK 73099 | Oil & Gas Operator | Jul 2025 |
| 353 | R & H LLC | Ardmore, OK 73401-6329 | Oil & Gas Operator | Mar 2015 |
| 354 | R & N Associates | Grapevine, TX 76051 | Oil & Gas Operator | Feb 2025 |
| 355 | R C Taylor Operating Company LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | Sep 2025 |
| 356 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 357 | Ramsey Property MGMT Inc | Oklahoma City, OK 73120-1955 | Oil & Gas Operator | Mar 2019 |
| 358 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 359 | Range Production Company, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Aug 2025 |
| 360 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Aug 2025 |
| 361 | Ratex Resources Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | May 2000 |
| 362 | Raven Resources LLC | Oklahoma City, OK 73172 | Oil & Gas Operator | Aug 2025 |
| 363 | Raw Crude Oil & Gas, L.L.C. | Norman, OK 73069 | Oil & Gas Operator | Aug 2025 |
| 364 | Rawhide Operating, Inc. | New Braunfels, TX 78131 | Oil & Gas Operator | Dec 2025 |
| 365 | Red Rocks Oil & Gas Operating LLC | Oklahoma City, OK 73103-4821 | Oil & Gas Operator | Sep 2025 |
| 366 | Redtail Investments LLC | Oklahoma City, OK 73179 | Oil & Gas Operator | Sep 2025 |
| 367 | Regency Exploration Inc | Oklahoma City, OK 73102-5605 | Oil & Gas Operator | Mar 1999 |
| 368 | Research Oil Company Inc | Norman, OK 73070-8776 | Oil & Gas Operator | Aug 2019 |
| 369 | Resources Investment Corp | Denver, CO 80202 | Oil & Gas Operator | Sep 2018 |
| 370 | Revelation Resources | Cypress, TX 77410-2578 | Oil & Gas Operator | Aug 2025 |
| 371 | Richland Resources Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Dec 2025 |
| 372 | Ricks Exploration Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Mar 2015 |
| 373 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | Sep 2025 |
| 374 | Rja Energy LLC | Norman, OK 73069-8224 | Oil & Gas Operator | Sep 2025 |
| 375 | RKK Production Company | Mustang, OK 73064 | Oil & Gas Operator | Sep 2025 |
| 376 | Roberson Oil Company | Houston, TX 77046 | Oil & Gas Operator | Sep 2025 |
| 377 | Robson Petroleum Company | Tulsa, OK 74104 | Oil & Gas Operator | Jan 1995 |
| 378 | Rockwell Energy Corporation | Tulsa, OK 74105 | Oil & Gas Operator | Apr 2014 |
| 379 | Roka Management Inc | Oklahoma City, OK 73139 | Oil & Gas Operator | Aug 2025 |
| 380 | Royalty Energy Development LLC | Edmond, OK 73003 | Oil & Gas Operator | Sep 2025 |
| 381 | Russell D Meloy Oil & Gas Co | Enid, OK 73703-1623 | Oil & Gas Operator | Aug 2025 |
| 382 | S & J Operating Company | Wichita Falls, TX 76301 | Oil & Gas Operator | Mar 2015 |
| 383 | S & M Production Inc | Pawnee, OK 74058 | Oil & Gas Operator | Aug 2023 |
| 384 | S/H Petroleum Corporation | Hennessey, OK 73742-0477 | Oil & Gas Operator | Feb 2016 |
| 385 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 386 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2025 |
| 387 | Sand Resources LLC | Norman, OK 73072-4805 | Oil & Gas Operator | Aug 2012 |
| 388 | Sandy Petroleum Inc | Shawnee, OK 74801-5634 | Oil & Gas Operator | Aug 2025 |
| 389 | Sanook Inc | Oklahoma City, OK 73156-0548 | Oil & Gas Operator | Jan 2007 |
| 390 | Santa Fe Energy Company | Midland, TX 79701 | Oil & Gas Operator | Dec 2015 |
| 391 | Santa Fe Energy Operating Partner LP | Midland, TX 79701 | Oil & Gas Operator | Sep 2004 |
| 392 | Scout Energy Corporation | Edmond, OK 73083-1348 | Oil & Gas Operator | Aug 2025 |
| 393 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 394 | Seagull Operating Co., Inc. | Shreveport, LA 71101 | Oil & Gas Operator | Jan 2025 |
| 395 | Seahawk Oil International Inc | Newport Beach, CA 92660 | Oil & Gas Operator | Oct 1997 |
| 396 | Sec Production Inc | Edmond, OK 73013-3709 | Oil & Gas Operator | Sep 2025 |
| 397 | Senax Inc | Tulsa, OK 74105-2206 | Oil & Gas Operator | Aug 2025 |
| 398 | Settlers Corporation | Oklahoma City, OK 73116 | Oil & Gas Operator | Nov 2000 |
| 399 | Shamrock Well Operations LLC | Oklahoma City, OK 73118-4015 | Oil & Gas Operator | Sep 2025 |
| 400 | Sharber Billy Jack Operating | Konawa, OK 74849-0071 | Oil & Gas Operator | Mar 2015 |