| 4201 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Dec 2025 |
| 4202 | Ok Production Services Inc | Broken Arrow, OK 74014 | Oil & Gas Operator | Aug 2025 |
| 4203 | Okc Energy Corporation | Oklahoma City, OK 73120-3119 | Oil & Gas Operator | Nov 2014 |
| 4204 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Aug 2025 |
| 4205 | Okie Oil Inc | Sapulpa, OK 74067-0290 | Oil & Gas Operator | Mar 2011 |
| 4206 | Okla Sub-Surface Pump & Supply Co | Seminole, OK 74804 | Oil & Gas Operator | Sep 2024 |
| 4207 | Oklahoma Basic Economy Corp | Houston, TX 77002-6003 | Oil & Gas Operator | Apr 2020 |
| 4208 | Oklahoma Cellulose Inc | Cleveland, OK 74020 | Oil Operator | Aug 2025 |
| 4209 | Oklahoma Crude Inc | Morris, OK 74445 | Oil & Gas Operator | Aug 2025 |
| 4210 | Oklahoma Crude Reclaimers, LLC | | Oil Operator | Sep 2025 |
| 4211 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Aug 2025 |
| 4212 | Oklahoma Energy Exchange LLC | Duncan, OK 73534-1105 | Oil & Gas Operator | Sep 2012 |
| 4213 | Oklahoma Energy LLC | Skiatook, OK 74070-3998 | Oil Operator | Apr 2025 |
| 4214 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 4215 | Oklahoma Gas & Oil Corp | | Oil Operator | Oct 2018 |
| 4216 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Aug 2025 |
| 4217 | Oklahoma Natural Resources Inc | Woodward, OK 73801 | Oil & Gas Operator | Sep 1996 |
| 4218 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 4219 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Aug 2025 |
| 4220 | Oklahoma Oil And Gas Resources LLC | Guthrie, OK 73044-8095 | Oil & Gas Operator | Sep 2025 |
| 4221 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 4222 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 4223 | Oklahoma Petroleum MGMT Corp | Tulsa, OK 74119 | Oil & Gas Operator | Jun 1993 |
| 4224 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 4225 | Oklahoma Prod & Exp Co | Broken Arrow, OK 74012 | Oil & Gas Operator | May 2013 |
| 4226 | Oklahoma Rig & Salvage Inc | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 4227 | Oklahoma SWD Systems Inc | Odessa, TX 79762-8132 | Oil & Gas Operator | Aug 2025 |
| 4228 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 4229 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Sep 2025 |
| 4230 | Oklaoleum Oil And Gas Inc | Bristow, OK 74010-0057 | Oil Operator | Jan 2016 |
| 4231 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 4232 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 4233 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 4234 | Oky Investments, Inc. | Edmond, OK 73013 | Oil & Gas Operator | Sep 2021 |
| 4235 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 4236 | Ole Crow Operating | Wichita Falls, TX 76308 | Oil Operator | Aug 2025 |
| 4237 | Oleum Inc | | Oil & Gas Operator | Mar 1996 |
| 4238 | Olia Oil & Gas Services LLC | Cedar Park, TX 78630-2049 | Oil & Gas Operator | Aug 2022 |
| 4239 | Oliphant Gertrud | Holdenville, OK 74848-0849 | Oil Operator | Aug 2013 |
| 4240 | Oliphant Operating Co,LTD,LLC | | Oil Operator | Aug 2025 |
| 4241 | Olive Oil & Gas Inc | Jennings, OK 74052 | Oil & Gas Operator | Aug 2025 |
| 4242 | Olympia Oil Inc | Edmond, OK 73083-7088 | Oil & Gas Operator | Jul 2020 |
| 4243 | Olympic Petroleum Co | Tulsa, OK 74114 | Oil & Gas Operator | Jun 1998 |
| 4244 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | Dec 2025 |
| 4245 | Omimex International Corp | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Aug 2025 |
| 4246 | Omimex Petroleum Inc | Fort Worth, TX 76120 | Oil & Gas Operator | Aug 2022 |
| 4247 | Omni Oil & Gas, Inc. | San Antonio, TX 78229 | Oil & Gas Operator | Oct 2017 |
| 4248 | On-Line Oil Inc | Oklahoma City, OK 73105-5208 | Oil & Gas Operator | Mar 2015 |
| 4249 | Onapa Gas Company LLC | Tulsa, OK 74136-7253 | Gas Operator | Nov 2019 |
| 4250 | Oneok Exploration Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 4251 | Oneok Field Services Company | Tulsa, OK 74103 | Oil & Gas Operator | Jul 2022 |
| 4252 | Oneok Gas Processing LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 4253 | Oneok Gas Transportation Co | Tulsa, OK 74121-2089 | Oil & Gas Operator | Oct 2014 |
| 4254 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 4255 | Onpoint Oil & Gas LLC | Oklahoma City, OK 73170-4848 | Oil & Gas Operator | Aug 2025 |
| 4256 | Onshore Royalties LLC | Houston, TX 77269 | Oil & Gas Operator | Sep 2025 |
| 4257 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 4258 | Onyx Properties Corp | Oklahoma City, OK 73114 | Oil & Gas Operator | May 2006 |
| 4259 | Opal Operating Company LLC | Edmond, OK 73013 | Oil & Gas Operator | Dec 2025 |
| 4260 | Open Door Holdings Inc | Surprise, AZ 85387-2015 | Oil & Gas Operator | Feb 2024 |
| 4261 | Open Door Productions Inc | Muskogee, OK 74401-1032 | Oil & Gas Operator | Apr 2020 |
| 4262 | Open Range Energy LLC | Jones, OK 73049-8744 | Oil & Gas Operator | Mar 2025 |
| 4263 | Optima Exploration LLC | Tulsa, OK 74116-5664 | Oil & Gas Operator | Mar 2015 |
| 4264 | Opubco Resources Of TX Inc | Dallas, TX 75231 | Oil & Gas Operator | Sep 2005 |
| 4265 | Oracle Resources Oklahoma LP | Dallas, TX 75240-5751 | Oil & Gas Operator | Feb 2008 |
| 4266 | Orason Resources Inc | Tulsa, OK 74169-1225 | Oil & Gas Operator | Nov 2006 |
| 4267 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Sep 2025 |
| 4268 | Oren Stone | Erick, OK 73645-4542 | Gas Operator | Jun 2022 |
| 4269 | Orion Exploration LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Apr 2015 |
| 4270 | Orion Exploration Partners LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Aug 2025 |
| 4271 | Orloski John C | Bartlesville, OK 74006 | Oil & Gas Operator | Jun 2025 |
| 4272 | Osa Oil & Gas LLC | Tulsa, OK 74131 | Oil & Gas Operator | Aug 2023 |
| 4273 | Osage Energy Resources LLC | Bartlesville, OK 74005-2527 | Oil & Gas Operator | Aug 2025 |
| 4274 | Osage Exploration & Development Inc | San Diego, CA 92131-3807 | Oil & Gas Operator | Oct 2016 |
| 4275 | Osage Oil & Transportation Inc | Cleveland, OK 74020 | Oil & Gas Operator | Nov 2000 |
| 4276 | Osage Petroleum Corporation | Saint Louis, MO 63131-4691 | Oil & Gas Operator | Mar 2009 |
| 4277 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 4278 | Osburn Gerald Dba Ozzy & Son Oil & Gas | Drumright, OK 74030-5467 | Oil Operator | Oct 2020 |
| 4279 | Oscar'S Well Service Inc | Okemah, OK 74859 | Oil & Gas Operator | Apr 1998 |
| 4280 | Oshtah Oil Company LLC | Stratford, OK 74872 | Oil & Gas Operator | Sep 2018 |
| 4281 | Oso Resources LLC | Edmond, OK 73003 | Oil & Gas Operator | Aug 2025 |
| 4282 | Osterhout Phillip L | Drumright, OK 74030-0693 | Oil & Gas Operator | Jan 2014 |
| 4283 | Oswego Arbuckle Enterprise Inc | S Coffeyville, OK 74072-9702 | Oil & Gas Operator | Mar 2015 |
| 4284 | Otc Investors Inc | | Oil Operator | Jun 2025 |
| 4285 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 4286 | Otc/Occ Not Assigned | | Oil & Gas Operator | Dec 2024 |
| 4287 | Ouachita Exploration Inc | Chickasha, OK 73018 | Oil & Gas Operator | Aug 2025 |
| 4288 | Outback Petroleum Inc | Moore, OK 73160-9998 | Oil & Gas Operator | Mar 2015 |
| 4289 | Outlaw Oil And Gas LLC | Kaw City, OK 74641 | Oil & Gas Operator | Aug 2025 |
| 4290 | Ovation Energy II, LP | Houston, TX 77279 | Oil & Gas Operator | Jun 2011 |
| 4291 | Ovation Energy, LP | N Richlnd HLS, TX 76180 | Oil & Gas Operator | Sep 2004 |
| 4292 | Overflow Energy Stack LLC | Booker, TX 79005 | Oil Operator | Sep 2022 |
| 4293 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Dec 2025 |
| 4294 | Overland Investments Inc | Coweta, OK 74429 | Oil & Gas Operator | Aug 2025 |
| 4295 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | Aug 2025 |
| 4296 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Dec 2025 |
| 4297 | Owens James W | Tulsa, OK 74114-1425 | Oil & Gas Operator | Oct 2022 |
| 4298 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 4299 | Oxco, LLC | | Oil & Gas Operator | Feb 2015 |
| 4300 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |