| 201 | Nova Energy Corporation | Denver, CO 80201 | Oil & Gas Operator | Jun 2003 |
| 202 | Oakland Petroleum Oper Co., Inc. | Kilgore, TX 75663 | Oil & Gas Operator | Jul 2025 |
| 203 | Odessa Oil Investment Co., Inc. | Odessa, TX 79762 | Oil & Gas Operator | Nov 2016 |
| 204 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 205 | Oklahoma SWD Systems Inc | Odessa, TX 79762-8132 | Oil & Gas Operator | Apr 2025 |
| 206 | Okland Oil Company | Oklahoma City, OK 73102-9022 | Oil & Gas Operator | May 2025 |
| 207 | Old Dominion Oil Corporation | Oklahoma City, OK 73107 | Oil & Gas Operator | Apr 2009 |
| 208 | Ole Crow Operating | Wichita Falls, TX 76308 | Oil Operator | May 2025 |
| 209 | Oneok Gas Processing LLC | Tulsa, OK 74103 | Oil & Gas Operator | May 2018 |
| 210 | Oneok Resources Company | Tulsa, OK 74102 | Oil & Gas Operator | Feb 2017 |
| 211 | Oren Stone | Erick, OK 73645-4542 | Gas Operator | Jun 2022 |
| 212 | Ovintiv Mid-Continent Inc. | The Woodlands, TX 77380-2764 | Oil & Gas Operator | May 2025 |
| 213 | Oxley Petroleum Co | Oklahoma City, OK 73118-1044 | Oil & Gas Operator | Sep 2017 |
| 214 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Jul 2025 |
| 215 | Paleo, Inc. | Oklahoma City, OK 73112 | Oil & Gas Operator | Jul 2025 |
| 216 | Panhandle Eastern Pipeline Company LP | Houston, TX 77002-6803 | Oil & Gas Operator | Oct 1999 |
| 217 | Panhandle Oil & Gas Inc | Oklahoma City, OK 73112-5688 | Oil & Gas Operator | May 2007 |
| 218 | Parker & Parsley Dev Co | Midland, TX 79702 | Oil & Gas Operator | Mar 2015 |
| 219 | Parker & Parsley Dev LP | Irving, TX 75039-3745 | Oil & Gas Operator | Mar 2015 |
| 220 | Penn VIrginia MC Operating Co LLC | Houston, TX 77084-7213 | Oil & Gas Operator | Jan 2025 |
| 221 | Pennzoil Petroleum Company | Houston, TX 77252 | Oil & Gas Operator | Nov 1999 |
| 222 | Perry L Larson Operating Co | Dallas, TX 75231-4712 | Oil & Gas Operator | Apr 2025 |
| 223 | Petro Speed Inc | Norman, OK 73069-8116 | Oil & Gas Operator | Mar 2015 |
| 224 | Petro-Hunt Corporation | Dallas, TX 75201 | Oil & Gas Operator | Jun 2003 |
| 225 | Petrohawk Operating Company | Houston, TX 77056 | Oil & Gas Operator | Oct 2021 |
| 226 | Petrolanic Inc | Tulsa, OK 74105 | Oil Operator | Oct 1991 |
| 227 | Petroleum Investment Inc | Oklahoma City, OK 73118 | Oil & Gas Operator | Nov 1998 |
| 228 | Petroleum Properties MGMT. Co. | Oklahoma City, OK 73118 | Oil & Gas Operator | Dec 2014 |
| 229 | Phoenix Operating Company, Inc. | Shreveport, LA 71161 | Oil & Gas Operator | Mar 2015 |
| 230 | Pioneer Natural Res. USA, Inc. | Spring, TX 77389 | Oil & Gas Operator | Jul 2025 |
| 231 | Plainsmen Energy LLC | Enid, OK 73703-5747 | Oil & Gas Operator | May 2025 |
| 232 | Plotner Ralph Oil & Gas Inv Co | Oklahoma City, OK 73112 | Oil & Gas Operator | Nov 2021 |
| 233 | Presidio Petroleum LLC | Canadian, TX 79014 | Oil & Gas Operator | Jul 2025 |
| 234 | Primary Natural Resources III LLC | Tulsa, OK 74136-6351 | Oil & Gas Operator | May 2025 |
| 235 | Prime Energy Corp | Charleston, WV 25301-1707 | Oil & Gas Operator | Sep 2015 |
| 236 | Princess Three Corporation | Henderson, TX 75653 | Oil & Gas Operator | Apr 2020 |
| 237 | Princess Three Operating, LLC | Henderson, TX 75653 | Oil & Gas Operator | Jul 2025 |
| 238 | Prize Operating Company | Grapevine, TX 76051 | Oil & Gas Operator | Aug 2016 |
| 239 | Pruitt Operating Company LLC | Ratliff City, OK 73481-5802 | Oil & Gas Operator | May 2025 |
| 240 | Qep Energy Company | Midland, TX 79701 | Oil & Gas Operator | Apr 2025 |
| 241 | Quantum Resources Management LLC | Houston, TX 77010 | Oil & Gas Operator | Apr 2025 |
| 242 | Questar Explor & Prod Co | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2017 |
| 243 | Ram Asset Management Co | Oklahoma City, OK 73114 | Oil & Gas Operator | Mar 2015 |
| 244 | Ramco Oil & Gas Inc | Midland, TX 79701 | Oil & Gas Operator | Nov 2006 |
| 245 | Range Production Company | Fort Worth, TX 76102 | Oil & Gas Operator | Sep 2021 |
| 246 | Ranken Energy Corporation | Edmond, OK 73013 | Oil & Gas Operator | Apr 2025 |
| 247 | Raw Crude Oil & Gas LLC | Norman, OK 73069 | Oil & Gas Operator | May 2025 |
| 248 | Red Hawk Resources Inc | Edmond, OK 73003-3207 | Oil & Gas Operator | May 2025 |
| 249 | Red Rocks Oil & Gas Operating LLC | Oklahoma City, OK 73103-4821 | Oil & Gas Operator | May 2025 |
| 250 | Revolution Resources LLC | Oklahoma City, OK 73134 | Oil & Gas Operator | Jun 2023 |
| 251 | Richland Resources Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Jul 2025 |
| 252 | Rimrock Gas Company | Weatherford, OK 73096 | Oil & Gas Operator | May 2008 |
| 253 | Riviera Operating, LLC | Houston, TX 77002 | Oil & Gas Operator | May 2025 |
| 254 | RKK Production Company | Mustang, OK 73064 | Oil & Gas Operator | May 2025 |
| 255 | RMS Monte Christo, LLC | Snowmass VLG., CO 81615 | Oil & Gas Operator | Mar 2023 |
| 256 | Sabine Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 257 | Samson Hydrocarbons Company | Tulsa, OK 74103 | Oil & Gas Operator | Nov 2016 |
| 258 | Samson Resources Company | Tulsa, OK 74103 | Oil & Gas Operator | Apr 2025 |
| 259 | Sandler Raymond C | Los Angeles, CA 90067 | Oil Operator | Dec 1999 |
| 260 | Sandridge Exploration And Production LLC | Oklahoma City, OK 73104 | Oil & Gas Operator | Jul 2025 |
| 261 | Sanguine Gas Exploration, LLC | Tulsa, OK 74119 | Oil & Gas Operator | Jul 2025 |
| 262 | Santa Fe Energy Operating Partner LP | Midland, TX 79701 | Oil & Gas Operator | Sep 2004 |
| 263 | Santa Fe Minerals, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Sep 2013 |
| 264 | Scambler Energy Group LTD Co | Colony, OK 73021 | Oil & Gas Operator | May 2025 |
| 265 | Scana Exploration Company | Houston, TX 77002 | Oil & Gas Operator | Dec 1999 |
| 266 | Scoggins Production LLC | Enid, OK 73703-3002 | Oil & Gas Operator | May 2025 |
| 267 | Scout Energy Management LLC | Dallas, TX 75240 | Oil & Gas Operator | Jul 2025 |
| 268 | Seagull Energy E & P Inc | Houston, TX 77002 | Oil & Gas Operator | Jan 2015 |
| 269 | Seagull Mid-South Inc | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 270 | Seagull Midcon Inc. | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 271 | Select Exploration Group LLC | Eufaula, OK 74432 | Oil & Gas Operator | May 2024 |
| 272 | Shell Oil Company | Houston, TX 77210 | Oil & Gas Operator | Apr 2015 |
| 273 | Sidwell Oil & Gas, Inc. | Amarillo, TX 79105 | Oil & Gas Operator | Sep 2014 |
| 274 | Siegfried R H Inc | Tulsa, OK 74104 | Oil & Gas Operator | Mar 2008 |
| 275 | Sierra Resources, Inc. | Oklahoma City, OK 73142 | Oil & Gas Operator | May 2025 |
| 276 | Skycap Energy, LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | May 2025 |
| 277 | SLT Dakota Operating, Inc. | Yukon, OK 73099 | Oil & Gas Operator | Jul 2025 |
| 278 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Jul 2025 |
| 279 | Snyder Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2015 |
| 280 | Sonata Oil & Gas Corp Inc | Stratford, OK 74812 | Oil & Gas Operator | Apr 2014 |
| 281 | Sooner Exploration & Development Co Inc | Enid, OK 73702-3525 | Oil & Gas Operator | Oct 2023 |
| 282 | Sooner Oil & Gas LLC | Fairview, OK 73737-1806 | Oil & Gas Operator | Apr 2025 |
| 283 | Sooner Oil & Gas Management Inc | Crescent, OK 73028 | Oil & Gas Operator | May 2025 |
| 284 | Southland Royalty Company | Houston, TX 77210 | Oil & Gas Operator | Sep 2011 |
| 285 | Special Energy Corporation | Stillwater, OK 74076 | Oil & Gas Operator | Jul 2025 |
| 286 | St. Mary Operating Company | Denver, CO 80203 | Oil & Gas Operator | Mar 2019 |
| 287 | Stephens Production Company | The Woodlands, TX 77381 | Oil & Gas Operator | May 2025 |
| 288 | Stewart K Petroleum Corp | Edmond, OK 73013 | Oil & Gas Operator | Mar 2015 |
| 289 | Sundown Energy LP | Dallas, TX 75248 | Oil & Gas Operator | Jul 2025 |
| 290 | Sundown Energy, Inc. | Dallas, TX 75240 | Oil & Gas Operator | Mar 2025 |
| 291 | Sweetwater Exploration LLC | Norman, OK 73069-5636 | Oil & Gas Operator | Apr 2025 |
| 292 | SWN Production LLC | Spring, TX 77389-4954 | Oil & Gas Operator | Feb 2022 |
| 293 | T & O Gas Co | | Oil Operator | May 2001 |
| 294 | Tapstone Energy LLC | Oklahoma City, OK 73101 | Oil & Gas Operator | May 2025 |
| 295 | Te-Ray Resources, LLC | Oklahoma City, OK 73142 | Oil & Gas Operator | Jul 2025 |
| 296 | Tecolote Energy Operating, LLC | Fort Worth, TX 76107 | Oil & Gas Operator | Jan 2024 |
| 297 | Temex Energy, Inc. | Oklahoma City, OK 73101 | Oil & Gas Operator | Feb 2002 |
| 298 | Templar Operating LLC | Oklahoma City, OK 73142 | Oil & Gas Operator | Apr 2025 |
| 299 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Apr 2025 |
| 300 | Teocalli Exploration LLC | Oklahoma City, OK 73118 | Oil & Gas Operator | May 2025 |