| 4201 | O G & E | Oklahoma City, OK 73124 | Oil & Gas Operator | Feb 2014 |
| 4202 | O K Swabbing Inc | Hennessey, OK 73742 | Oil & Gas Operator | Nov 2025 |
| 4203 | O'Blue Corp. | Kerrville, TX 78028 | Oil & Gas Operator | Mar 1998 |
| 4204 | O'Brien Energy Resources Corp | Portsmouth, NH 03801 | Oil & Gas Operator | Dec 2025 |
| 4205 | O'Brien Oil Corporation | Guthrie, OK 73044-3154 | Oil & Gas Operator | Oct 2025 |
| 4206 | O'Brien Oil LLC | Guthrie, OK 73044-3154 | Oil & Gas Operator | Apr 2020 |
| 4207 | O'Brien Resources LLC | Shreveport, LA 71136 | Oil Operator | Nov 2017 |
| 4208 | O'Donnell Bill C | Tulsa, OK 74135-4241 | Oil & Gas Operator | Oct 2014 |
| 4209 | O'Hern Morris D | Mounds, OK 74047-5163 | Oil & Gas Operator | Sep 2016 |
| 4210 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | Nov 2025 |
| 4211 | O'Neal Oil Company | Nocona, TX 76255 | Oil & Gas Operator | Dec 2025 |
| 4212 | O'Neal, Lindell | Nocona, TX 76255 | Oil & Gas Operator | Oct 2025 |
| 4213 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Dec 2025 |
| 4214 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Dec 2025 |
| 4215 | O7 Saltwater Disposal LLC | Marietta, OK 73448 | Oil Operator | Oct 2025 |
| 4216 | Oak Hill Petroleum Corporation | Oklahoma City, OK 73116-5627 | Oil & Gas Operator | Oct 2025 |
| 4217 | Oak Hills Drilling & Oper., LLC | Holdenville, OK 74848 | Oil & Gas Operator | May 2013 |
| 4218 | Oak Hills Energy Inc | Holdenville, OK 74848-0470 | Oil & Gas Operator | Sep 2014 |
| 4219 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 4220 | Oak Tree Natural Res LLC | Oklahoma City, OK 73120-5065 | Oil & Gas Operator | Mar 2015 |
| 4221 | Oak Valley SWD LLC | Enid, OK 73703-4637 | Oil Operator | Aug 2022 |
| 4222 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Dec 2025 |
| 4223 | Oakwood Resources Inc | Dallas, TX 75374 | Oil & Gas Operator | May 1998 |
| 4224 | Oasis Energy Resources LLC | Norman, OK 73072-9668 | Oil & Gas Operator | Jun 2025 |
| 4225 | Obele Oil Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | May 2017 |
| 4226 | Obele Operating Company LLC | Sedona, AZ 86336-5745 | Oil & Gas Operator | Oct 2025 |
| 4227 | Oberlander Leslie A Jake | Covington, OK 73730 | Oil Operator | Jun 2007 |
| 4228 | Ochiltree Oil Company | Edmond, OK 73034 | Oil & Gas Operator | Apr 2020 |
| 4229 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 4230 | Odell Larry | Oologah, OK 74053 | Oil Operator | Apr 2011 |
| 4231 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 4232 | Odum Ronald L | Ponca City, OK 74601 | Oil Operator | Oct 2025 |
| 4233 | Oex-1 LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Mar 2024 |
| 4234 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 4235 | Offield Lease Operations LLC | Wilson, OK 73463 | Oil & Gas Operator | May 2023 |
| 4236 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 4237 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 4238 | Oil & Gas Unlimited Inc | | Oil & Gas Operator | May 2013 |
| 4239 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 4240 | Oil Creek Production Company | Prague, OK 74864-0667 | Oil & Gas Operator | Sep 2025 |
| 4241 | Oil Exploration Of America Inc | Sisseton, SD 57262-9503 | Oil & Gas Operator | Jun 2001 |
| 4242 | Oil Investors Inc | Crescent, OK 73028 | Oil & Gas Operator | Nov 2025 |
| 4243 | Oil Lift Inc | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 4244 | Oil Operations Inc | | Oil & Gas Operator | Apr 2011 |
| 4245 | Oil Patch Energy LLC | Broken Arrow, OK 74014 | Oil & Gas Operator | Oct 2025 |
| 4246 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Nov 2025 |
| 4247 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Dec 2025 |
| 4248 | Oil Production Management Inc | Squaw Valley, CA 93675-9725 | Oil & Gas Operator | Dec 2002 |
| 4249 | Oil Production Systems Inc | Cushing, OK 74023 | Oil & Gas Operator | Jan 2013 |
| 4250 | Oil Property Management Inc | Attica, KS 67009 | Oil & Gas Operator | Feb 2021 |
| 4251 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Oct 2025 |
| 4252 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Nov 2025 |
| 4253 | Oil Ventures LTD | | Oil & Gas Operator | Jan 2013 |
| 4254 | Oilbank Production LLC | Norman, OK 73072 | Oil Operator | Oct 2025 |
| 4255 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 4256 | Oilfield Leasing Inc | Cushing, OK 74023-0967 | Oil & Gas Operator | Aug 2018 |
| 4257 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 4258 | Oilrox Resources LLC | San Antonio, TX 78258 | Oil & Gas Operator | Nov 2025 |
| 4259 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 4260 | Oilton Petroleum Inc | Oilton, OK 74052-0459 | Oil & Gas Operator | Oct 2001 |
| 4261 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Dec 2025 |
| 4262 | Ok Production Services Inc | Broken Arrow, OK 74014 | Oil & Gas Operator | Oct 2025 |
| 4263 | Okc Energy Corporation | Oklahoma City, OK 73120-3119 | Oil & Gas Operator | Nov 2014 |
| 4264 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Oct 2025 |
| 4265 | Okie Oil Inc | Sapulpa, OK 74067-0290 | Oil & Gas Operator | Mar 2011 |
| 4266 | Okla Sub-Surface Pump & Supply Co | Seminole, OK 74804 | Oil & Gas Operator | Sep 2024 |
| 4267 | Oklahoma Basic Economy Corp | Houston, TX 77002-6003 | Oil & Gas Operator | Apr 2020 |
| 4268 | Oklahoma Cellulose Inc | Cleveland, OK 74020 | Oil Operator | Oct 2025 |
| 4269 | Oklahoma Crude Inc | Morris, OK 74445 | Oil & Gas Operator | Oct 2025 |
| 4270 | Oklahoma Crude Reclaimers, LLC | | Oil Operator | Nov 2025 |
| 4271 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Nov 2025 |
| 4272 | Oklahoma Energy Exchange LLC | Duncan, OK 73534-1105 | Oil & Gas Operator | Sep 2012 |
| 4273 | Oklahoma Energy LLC | Skiatook, OK 74070-3998 | Oil Operator | Apr 2025 |
| 4274 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 4275 | Oklahoma Gas & Oil Corp | | Oil Operator | Oct 2018 |
| 4276 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Oct 2025 |
| 4277 | Oklahoma Natural Resources Inc | Woodward, OK 73801 | Oil & Gas Operator | Sep 1996 |
| 4278 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 4279 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Oct 2025 |
| 4280 | Oklahoma Oil And Gas Resources LLC | Guthrie, OK 73044-8095 | Oil & Gas Operator | Nov 2025 |
| 4281 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 4282 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 4283 | Oklahoma Petroleum MGMT Corp | Tulsa, OK 74119 | Oil & Gas Operator | Jun 1993 |
| 4284 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 4285 | Oklahoma Prod & Exp Co | Broken Arrow, OK 74012 | Oil & Gas Operator | May 2013 |
| 4286 | Oklahoma Rig & Salvage Inc | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 4287 | Oklahoma SWD Systems Inc | Odessa, TX 79762-8132 | Oil & Gas Operator | Oct 2025 |
| 4288 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 4289 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | Nov 2025 |
| 4290 | Oklaoleum Oil And Gas Inc | Bristow, OK 74010-0057 | Oil Operator | Jan 2016 |
| 4291 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 4292 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 4293 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 4294 | Oky Investments, Inc. | Edmond, OK 73013 | Oil & Gas Operator | Sep 2021 |
| 4295 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 4296 | Ole Crow Operating | Wichita Falls, TX 76308 | Oil Operator | Oct 2025 |
| 4297 | Oleum Inc | | Oil & Gas Operator | Mar 1996 |
| 4298 | Olia Oil & Gas Services LLC | Cedar Park, TX 78630-2049 | Oil & Gas Operator | Aug 2022 |
| 4299 | Oliphant Gertrud | Holdenville, OK 74848-0849 | Oil Operator | Aug 2013 |
| 4300 | Oliphant Operating Co,LTD,LLC | | Oil Operator | Oct 2025 |