| 4101 | O'Brien Energy Resources Corp | Portsmouth, NH 03801 | Oil & Gas Operator | Jul 2025 |
| 4102 | O'Brien Oil Corporation | Guthrie, OK 73044-3154 | Oil & Gas Operator | Apr 2025 |
| 4103 | O'Brien Oil LLC | Guthrie, OK 73044-3154 | Oil & Gas Operator | Apr 2020 |
| 4104 | O'Brien Resources LLC | Shreveport, LA 71136 | Oil Operator | Nov 2017 |
| 4105 | O'Donnell Bill C | Tulsa, OK 74135-4241 | Oil & Gas Operator | Oct 2014 |
| 4106 | O'Hern Morris D | Mounds, OK 74047-5163 | Oil & Gas Operator | Sep 2016 |
| 4107 | O'Neal Oil & Gas Co | Fort Worth, TX 76107-1479 | Oil & Gas Operator | May 2025 |
| 4108 | O'Neal Oil Company | Nocona, TX 76255 | Oil & Gas Operator | Jul 2025 |
| 4109 | O'Neal, Lindell | Nocona, TX 76255 | Oil & Gas Operator | Apr 2025 |
| 4110 | O'Neill Properties, LTD. | Midland, TX 79702 | Oil & Gas Operator | Jul 2025 |
| 4111 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | Jul 2025 |
| 4112 | Oak Hill Petroleum Corporation | Oklahoma City, OK 73116-5627 | Oil & Gas Operator | Feb 2025 |
| 4113 | Oak Hills Drilling & Oper., LLC | Holdenville, OK 74848 | Oil & Gas Operator | May 2013 |
| 4114 | Oak Hills Energy Inc | Holdenville, OK 74848-0470 | Oil & Gas Operator | Sep 2014 |
| 4115 | Oak Resources Inc | Tulsa, OK 74153 | Oil & Gas Operator | Aug 2013 |
| 4116 | Oak Tree Natural Res LLC | Oklahoma City, OK 73120-5065 | Oil & Gas Operator | Mar 2015 |
| 4117 | Oak Valley SWD LLC | Enid, OK 73703-4637 | Oil Operator | Aug 2022 |
| 4118 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 4119 | Oakwood Resources, Inc. | Dallas, TX 75374 | Oil & Gas Operator | May 1998 |
| 4120 | Oasis Energy Resources LLC | Norman, OK 73072-9668 | Oil & Gas Operator | Apr 2025 |
| 4121 | Obele Oil Corporation | Sedona, AZ 86336-5745 | Oil & Gas Operator | May 2017 |
| 4122 | Obele Operating Company LLC | Sedona, AZ 86336-5745 | Oil & Gas Operator | Apr 2025 |
| 4123 | Oberlander Leslie A Jake | Covington, OK 73730 | Oil Operator | Jun 2007 |
| 4124 | Ochiltree Oil Company | Edmond, OK 73034 | Oil & Gas Operator | Apr 2020 |
| 4125 | Octagon Resources LLC | Norman, OK 73071-1295 | Oil & Gas Operator | May 2015 |
| 4126 | Odell Larry | Oologah, OK 74053 | Oil Operator | Apr 2011 |
| 4127 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 4128 | Odum Ronald L | Garfield, AR 72732 | Oil Operator | Apr 2025 |
| 4129 | Oex-1 LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Mar 2024 |
| 4130 | Oexco, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2015 |
| 4131 | Offield Lease Operations LLC | Wilson, OK 73463 | Oil & Gas Operator | May 2023 |
| 4132 | Ofs-Tulsa Corporation | Fort Worth, TX 76102 | Oil & Gas Operator | Feb 1997 |
| 4133 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 4134 | Oil & Gas Unlimited Inc | | Oil & Gas Operator | May 2013 |
| 4135 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 4136 | Oil Creek Production Company | Prague, OK 74864-0667 | Oil & Gas Operator | Feb 2025 |
| 4137 | Oil Exploration Of America Inc | Sisseton, SD 57262-9503 | Oil & Gas Operator | Jun 2001 |
| 4138 | Oil Investors Inc | Crescent, OK 73028 | Oil & Gas Operator | May 2025 |
| 4139 | Oil Lift, Incorporated | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 4140 | Oil Operations Inc | | Oil & Gas Operator | Apr 2011 |
| 4141 | Oil Patch Energy LLC | Broken Arrow, OK 74014 | Oil & Gas Operator | Jan 2025 |
| 4142 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Apr 2025 |
| 4143 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Jul 2025 |
| 4144 | Oil Production Management Inc | Squaw Valley, CA 93675-9725 | Oil & Gas Operator | Dec 2002 |
| 4145 | Oil Production Systems Inc | Cushing, OK 74023 | Oil & Gas Operator | Jan 2013 |
| 4146 | Oil Property Management, Inc. | Attica, KS 67009 | Oil & Gas Operator | Feb 2021 |
| 4147 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Apr 2025 |
| 4148 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Mar 2025 |
| 4149 | Oil Ventures LTD | | Oil & Gas Operator | Jan 2013 |
| 4150 | Oilbank Production LLC | Norman, OK 73072 | Oil Operator | Apr 2025 |
| 4151 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 4152 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 4153 | Oilrox Resources LLC | San Antonio, TX 78258 | Oil & Gas Operator | May 2025 |
| 4154 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 4155 | Oilton Petroleum Inc | Oilton, OK 74052-0459 | Oil & Gas Operator | Oct 2001 |
| 4156 | Oilwell Operators, Inc. | Pampa, TX 79066 | Oil & Gas Operator | Jul 2025 |
| 4157 | Okc Energy Corporation | Oklahoma City, OK 73120-3119 | Oil & Gas Operator | Nov 2014 |
| 4158 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 4159 | Okie Oil Inc | Sapulpa, OK 74067-0290 | Oil & Gas Operator | Mar 2011 |
| 4160 | Okla Sub-Surface Pump & Supply Co | Seminole, OK 74804 | Oil & Gas Operator | Sep 2024 |
| 4161 | Oklahoma Basic Economy Corp | Houston, TX 77002-6003 | Oil & Gas Operator | Apr 2020 |
| 4162 | Oklahoma Cellulose Inc | Cleveland, OK 74020 | Oil Operator | Apr 2025 |
| 4163 | Oklahoma Crude Inc | Morris, OK 74445 | Oil & Gas Operator | Apr 2024 |
| 4164 | Oklahoma Crude Reclaimers, LLC | | Oil Operator | May 2025 |
| 4165 | Oklahoma Energy Acquisitions LP | Houston, TX 77094-1900 | Oil & Gas Operator | Apr 2025 |
| 4166 | Oklahoma Energy Exchange LLC | Duncan, OK 73534-1105 | Oil & Gas Operator | Sep 2012 |
| 4167 | Oklahoma Energy LLC | Skiatook, OK 74070-3998 | Oil Operator | Apr 2025 |
| 4168 | Oklahoma Equipment & Salvage | Oklahoma City, OK 73120-5903 | Oil & Gas Operator | Mar 2015 |
| 4169 | Oklahoma Gas & Oil Corp | | Oil Operator | Oct 2018 |
| 4170 | Oklahoma Liquid Resources Inc | Collinsville, OK 74021 | Oil & Gas Operator | Apr 2025 |
| 4171 | Oklahoma Natural Resources Inc | Woodward, OK 73801 | Oil & Gas Operator | Sep 1996 |
| 4172 | Oklahoma O & G Royalties Inc | Duncan, OK 73533 | Oil & Gas Operator | Nov 2000 |
| 4173 | Oklahoma Oil & Gas MGMT Inc | Edmond, OK 73083-6786 | Oil & Gas Operator | Apr 2025 |
| 4174 | Oklahoma Oil And Gas Resources LLC | Guthrie, OK 73044-8095 | Oil & Gas Operator | Apr 2025 |
| 4175 | Oklahoma Oil Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2013 |
| 4176 | Oklahoma Oil Tactics Inc | Edmond, OK 73003-1351 | Oil & Gas Operator | Mar 2015 |
| 4177 | Oklahoma Petroleum MGMT Corp | Tulsa, OK 74119 | Oil & Gas Operator | Jun 1993 |
| 4178 | Oklahoma Prime Energy LLC | Ardmore, OK 73401 | Oil Operator | May 2020 |
| 4179 | Oklahoma Prod & Exp Co | Broken Arrow, OK 74012 | Oil & Gas Operator | May 2013 |
| 4180 | Oklahoma Rig & Salvage, Inc. | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 4181 | Oklahoma SWD Systems Inc | Odessa, TX 79762-8132 | Oil & Gas Operator | Apr 2025 |
| 4182 | Oklahoma Tank Service Inc | Oklahoma City, OK 73143 | Oil Operator | Aug 1997 |
| 4183 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | May 2025 |
| 4184 | Oklaoleum Oil And Gas Inc | Bristow, OK 74010-0057 | Oil Operator | Jan 2016 |
| 4185 | Okmar Oil Company | Marietta, OH 45750 | Oil & Gas Operator | Jun 2005 |
| 4186 | Okt Petroleum Company Inc | Oklahoma City, OK 73118-7425 | Oil & Gas Operator | Oct 2013 |
| 4187 | Oktex Operating LLC | Edmond, OK 73013-1961 | Oil & Gas Operator | May 2020 |
| 4188 | Oky Investments, Inc. | Edmond, OK 73013 | Oil & Gas Operator | Sep 2021 |
| 4189 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 4190 | Ole Crow Operating | Wichita Falls, TX 76308 | Oil Operator | May 2025 |
| 4191 | Oleum Incorporated | | Oil & Gas Operator | Mar 1996 |
| 4192 | Olia Oil & Gas Services LLC | Cedar Park, TX 78630-2049 | Oil & Gas Operator | Aug 2022 |
| 4193 | Oliphant Gertrud | Holdenville, OK 74848-0849 | Oil Operator | Aug 2013 |
| 4194 | Oliphant Operating Co,LTD,LLC | | Oil Operator | Apr 2025 |
| 4195 | Olive Oil & Gas Inc | Jennings, OK 74052 | Oil & Gas Operator | Mar 2025 |
| 4196 | Olympia Oil Inc | Edmond, OK 73083-7088 | Oil & Gas Operator | Jul 2020 |
| 4197 | Olympic Petroleum Company | Tulsa, OK 74114 | Oil & Gas Operator | Jun 1998 |
| 4198 | Omega Energy, LLC | Corpus Chrsti, TX 78418 | Oil & Gas Operator | Jul 2025 |
| 4199 | Omega Mid-Continent, LLC | Tulsa, OK 74170 | Oil Operator | Apr 2025 |
| 4200 | Omimex International Corporation | Fort Worth, TX 76103-2300 | Oil & Gas Operator | Apr 2025 |