| 201 | Oro Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Oct 2025 |
| 202 | Orr Production Company | Austin, TX 78746 | Oil & Gas Operator | Dec 2000 |
| 203 | Orr, Robert M. | Monahans, TX 79756 | Oil & Gas Operator | Oct 1998 |
| 204 | Orsburn, Wade Inc. | Gainesville, TX 76240 | Oil & Gas Operator | Nov 2002 |
| 205 | Orson Leasing & Supply | Rockdale, TX 76567 | Oil & Gas Operator | Dec 2006 |
| 206 | Orth Oil Company, Inc. | Cisco, TX 76437 | Oil & Gas Operator | Oct 2025 |
| 207 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Oct 2025 |
| 208 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 209 | Os&S Operating Inc. | Electra, TX 76360 | Oil & Gas Operator | Oct 2025 |
| 210 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Aug 2025 |
| 211 | Osborn,W.B. Oil & Gas Operations | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 212 | Osborne Oil Co. | Dallas, TX 75244 | Oil & Gas Operator | Aug 2003 |
| 213 | Oscar Oil Company | Iowa Park, TX 76367 | Oil & Gas Operator | Sep 2004 |
| 214 | Osceola Oil & Gas Corporation | Somerset, TX 78069 | Oil & Gas Operator | Aug 1994 |
| 215 | Oso Exploration & Production, LLC | Houston, TX 77269 | Oil Operator | Oct 2025 |
| 216 | Oso Exploration Co. | San Antonio, TX 78217 | Oil & Gas Operator | Jul 2011 |
| 217 | Osprey Petroleum Company, Inc. | Manvel, TX 77578 | Oil & Gas Operator | May 2020 |
| 218 | Osr Oil & Gas Company | Victoria, TX 77902 | Oil & Gas Operator | Jul 2000 |
| 219 | Osr Oil & Gas Corp | Midland, TX 79710 | Oil & Gas Operator | Dec 2024 |
| 220 | Ostrich Oil & Gas, LLC | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 221 | Oswego, Inc. | Amarillo, TX 79109 | Oil & Gas Operator | Jun 2004 |
| 222 | Osyka Oil & Gas, Inc. | Metairie, LA 70004 | Oil & Gas Operator | Oct 2025 |
| 223 | Osyka Permian, LLC | Houston, TX 77079 | Oil & Gas Operator | Oct 2025 |
| 224 | Osyka Producing Company, Inc. | Houston, TX 77242 | Oil & Gas Operator | Oct 2025 |
| 225 | Otb Operating, LLC | Stanton, TX 79782 | Oil & Gas Operator | Oct 2025 |
| 226 | Otc Petroleum Corporation | Nichols Hill, OK 73116 | Oil & Gas Operator | Mar 2015 |
| 227 | Otex LLC | Santa Anna, TX 76878 | Oil & Gas Operator | Oct 2025 |
| 228 | Otex Resources LLC | Baytown, TX 77520 | Oil & Gas Operator | Oct 2025 |
| 229 | Oto, Co. | Woodward, OK 73802 | Oil & Gas Operator | Jun 1998 |
| 230 | Ouachita Exploration Inc | Chickasha, OK 73018 | Oil & Gas Operator | Jun 2025 |
| 231 | Ouida Oil | Rowlett, TX 75030 | Oil & Gas Operator | Mar 2008 |
| 232 | Outlaw Oil LLC | Caldwell, TX 77836 | Oil & Gas Operator | Oct 2025 |
| 233 | Outline Oil Company LLC | Beeville, TX 78104 | Oil Operator | Oct 2025 |
| 234 | Outline Oil Corp. | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 235 | Ouut Investing LLC | Mineral Wells, TX 76068 | Oil Operator | Mar 2020 |
| 236 | Ovation Energy II, LP | Houston, TX 77279 | Oil & Gas Operator | Jun 2011 |
| 237 | Ovation Energy, LP | N Richlnd HLS, TX 76180 | Oil & Gas Operator | Sep 2004 |
| 238 | Overflow Energy, LLC | Perryton, TX 79070 | Oil & Gas Operator | Oct 2025 |
| 239 | Overland Operating Company, LLC | Abilene, TX 79601 | Oil Operator | Oct 2025 |
| 240 | Overly Operating Co. | San Antonio, TX 78209 | Oil & Gas Operator | Jul 2013 |
| 241 | Overstreet, Jamie L | Hondo, TX 78861 | Oil & Gas Operator | Oct 2025 |
| 242 | Overton Park Oil & Gas LP | Fort Worth, TX 76109 | Oil & Gas Operator | Oct 2025 |
| 243 | Ovintiv USA Inc. | Denver, CO 80202 | Oil & Gas Operator | Oct 2025 |
| 244 | Owens Oil Company | Iowa Park, TX 76367 | Oil & Gas Operator | Sep 2008 |
| 245 | Owens Petroleum, Inc. | Midland, TX 79702 | Oil & Gas Operator | Aug 1995 |
| 246 | Owl Creek Operating Co., Inc. | Denver, CO 80206 | Oil & Gas Operator | Oct 2025 |
| 247 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 248 | Owl Creek Production Co., LLC | Denver, CO 80265 | Oil & Gas Operator | Jan 2006 |
| 249 | Owl Operating Ventures L.L.C. | Midland, TX 79708 | Oil & Gas Operator | Dec 2022 |
| 250 | Owl Ops II LLC | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 251 | Owl Ops LLC | Midland, TX 79701 | Oil & Gas Operator | Oct 2025 |
| 252 | Own Resources Operating LLC | The Woodlands, TX 77381 | Oil & Gas Operator | Jul 2025 |
| 253 | Ows Energy, Inc. | Montgomery, TX 77356 | Oil & Gas Operator | Oct 2025 |
| 254 | Oxbow EP LLC | Mathis, TX 78368 | Oil Operator | Oct 2025 |
| 255 | Oxbow Petroleum, LLC | Midland, TX 79703 | Oil & Gas Operator | May 2025 |
| 256 | Oxenergy Incorporated | Flower Mound, TX 75022 | Oil & Gas Operator | Oct 2025 |
| 257 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |
| 258 | Oxford Oil Co. | Rockdale, TX 76567 | Oil & Gas Operator | Aug 2004 |
| 259 | Oxson Co. | Uvalde, TX 78802 | Gas Operator | Oct 2025 |
| 260 | Oxxn | Weatherford, TX 76086 | Oil & Gas Operator | Oct 2023 |
| 261 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 262 | Oxy USA WTP LP | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 263 | Oxyrock Operating, LLC | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |
| 264 | Oz Gas Corporation | Austin, TX 78746 | Gas Operator | Oct 2025 |
| 265 | Ozark Exploration, Inc. | Dallas, TX 75205 | Oil & Gas Operator | Oct 2025 |
| 266 | Oztx Oil & Gas, L.L.C. | Ozona, TX 76943 | Oil & Gas Operator | Oct 2025 |
| 267 | Ozzo Corporation, The | Bedford, TX 76021 | Oil Operator | Oct 2025 |