| 3201 | O'Sullivan Oil & Gas Co., Inc. | Houston, TX 77002 | Oil & Gas Operator | Sep 2000 |
| 3202 | O. B. And Keith Whatley | | Oil Operator | Jul 1993 |
| 3203 | O. B. Beck | | Oil Operator | Feb 1991 |
| 3204 | O. B. Mobley | | Oil & Gas Operator | Jul 1989 |
| 3205 | O. B. Mobley, Et Al | | Oil Operator | Jul 1989 |
| 3206 | O. B. Whatley | | Oil Operator | Jul 1993 |
| 3207 | O. D. Maybrier | | Oil Operator | Dec 2011 |
| 3208 | O. F. H., Inc. | | Oil Operator | May 1990 |
| 3209 | O. G., Inc. | | Oil & Gas Operator | Nov 1992 |
| 3210 | O. O. Cummings | | Gas Operator | Jan 1999 |
| 3211 | O.B. Whatley Oil Company, Inc. | | Oil Operator | Feb 2013 |
| 3212 | O.B., Keith & Owen B. Whatley | | Oil Operator | Jul 1989 |
| 3213 | O.G.P. Operating, Inc. | Dallas, TX 75231 | Oil & Gas Operator | May 2024 |
| 3214 | O.I.L. Energy, Inc. | | Oil & Gas Operator | Dec 1984 |
| 3215 | Oak Energy, LLC | Houston, TX 77027 | Oil & Gas Operator | May 2024 |
| 3216 | Oak Valley Operating, LLC | The Woodlands, TX 77380 | Oil & Gas Operator | Jun 2015 |
| 3217 | Oakfield Energy LLC | | Oil Operator | Jun 2019 |
| 3218 | Oakland Corporation | Shreveport, LA 71135 | Oil & Gas Operator | Dec 1981 |
| 3219 | Oakley Oil & Gas, L.L.C. | | Oil & Gas Operator | Mar 2012 |
| 3220 | Oasis Production Co., Inc. | | Oil & Gas Operator | Jun 1988 |
| 3221 | Occ Operating Co. | | Oil & Gas Operator | Apr 2019 |
| 3222 | Occidental Energy Company, Inc. | Houston, TX 77282 | Oil & Gas Operator | Jul 2021 |
| 3223 | Ocean Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | Aug 2003 |
| 3224 | Octagon Resources Corporation | | Oil Operator | Mar 2005 |
| 3225 | Ody Oil Corp. | | Oil & Gas Operator | Oct 1994 |
| 3226 | Odyssey Operating Company | Shreveport, LA 71106 | Oil & Gas Operator | Sep 2020 |
| 3227 | Offshore Oil & Gas Inc | Houston, TX 77063 | Oil & Gas Operator | Sep 1994 |
| 3228 | Offshore Shelf LLC | | Oil & Gas Operator | Dec 2007 |
| 3229 | Oil & Gas Development Company | | Oil & Gas Operator | May 1991 |
| 3230 | Oil & Gas Producers, Inc. | Topeka, KS 66604 | Oil Operator | Jun 2004 |
| 3231 | Oil & Gas Property MGMT., Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 1996 |
| 3232 | Oil And Gas Futures, Inc. | | Oil & Gas Operator | May 1977 |
| 3233 | Oil Country Management, Inc. | | Oil & Gas Operator | Jan 2005 |
| 3234 | Oil Lift, Incorporated | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 3235 | Oil Palace, Inc. | | Oil Operator | May 2016 |
| 3236 | Oil Patch Operators, LLC | | Oil & Gas Operator | Jul 2005 |
| 3237 | Oil Recovery, Inc. | | Oil Operator | Sep 1992 |
| 3238 | Oil Reserves Corp Of America | | Oil & Gas Operator | May 2002 |
| 3239 | Oil Well Buyers Corp. | Houston, TX 77056 | Oil & Gas Operator | Jan 2024 |
| 3240 | Oil,Gas & Other Minerals, Inc. | | Oil & Gas Operator | Apr 1996 |
| 3241 | Oilwell Acquisition Co. | | Oil & Gas Operator | Jun 1999 |
| 3242 | Ok Oil Company, Inc. | Bivins, TX 75555 | Oil & Gas Operator | Feb 2013 |
| 3243 | Ok-La-Tex Production, Inc. | | Oil & Gas Operator | Jan 1982 |
| 3244 | Okie Crude Company | Tulsa, OK 74103 | Oil & Gas Operator | Jan 2024 |
| 3245 | Okie Operating Company, LTD. | Tulsa, OK 74103 | Oil & Gas Operator | May 2024 |
| 3246 | Okkatahula, Inc. | | Oil Operator | Nov 1978 |
| 3247 | Oldfield Operating Corporation | | Oil Operator | Dec 2013 |
| 3248 | Oleum Incorporated | | Oil & Gas Operator | Mar 1996 |
| 3249 | Oleum Operating Company, L.C. | Longview, TX 75606 | Oil & Gas Operator | Dec 2021 |
| 3250 | Oleum Operating La LLC | | Oil & Gas Operator | Nov 2022 |
| 3251 | Oliditt Corporation | | Gas Operator | Mar 2022 |
| 3252 | Oliditt Production Inc. | | Gas Operator | Sep 1998 |
| 3253 | Olipdp II, LLC | Tulsa, OK 74119 | Oil & Gas Operator | May 2024 |
| 3254 | Olympic Natural Gas Company | | Oil & Gas Operator | Oct 1990 |
| 3255 | Olympic Oil & Gas Co., Inc. | | Oil Operator | Apr 1991 |
| 3256 | Olympic Petroleum Company | Tulsa, OK 74114 | Oil & Gas Operator | Jun 1998 |
| 3257 | Olympic Production Company | | Oil & Gas Operator | Jul 1994 |
| 3258 | Omeara Bros. | | Oil & Gas Operator | Oct 1982 |
| 3259 | Omega Energy Corp. | Graham, TX 76450 | Oil & Gas Operator | May 2024 |
| 3260 | Omega Energy Incorporated | | Oil & Gas Operator | May 1998 |
| 3261 | Omni Operating Company | Osage, WY 82723 | Oil & Gas Operator | Sep 2001 |
| 3262 | Onshore Exp Cor-La Nat Res Inc | | Oil & Gas Operator | Oct 1978 |
| 3263 | Onshore Pipeline Const Co Inc | | Oil & Gas Operator | Aug 1998 |
| 3264 | Onyx Energy Corporation | Oklahoma City, OK 73157 | Oil & Gas Operator | May 1994 |
| 3265 | Onyx Energy Dev Of Texas Inc. | | Oil Operator | Dec 1996 |
| 3266 | Onyx Energy Of Texas Inc. | | Oil Operator | Dec 1996 |
| 3267 | Onyxx Energy LLC | | Oil & Gas Operator | Mar 2017 |
| 3268 | Opal Oil Inc. | | Oil Operator | Sep 2021 |
| 3269 | Opmi Operating Company | Houston, TX 77057 | Oil & Gas Operator | Jun 2008 |
| 3270 | Ops Group Limited | Houston, TX 77060 | Oil & Gas Operator | Jun 2014 |
| 3271 | Optimistic Oil Co. | | Oil & Gas Operator | Dec 1991 |
| 3272 | Ora Oil Company | | Oil & Gas Operator | May 2017 |
| 3273 | Oracle Oil, LLC | | Oil & Gas Operator | Jul 2013 |
| 3274 | Orb Exploration, L.L.C. | | Oil & Gas Operator | Jun 2017 |
| 3275 | Orion Oil & Gas, LLC | Houston, TX 77042 | Oil & Gas Operator | Oct 2007 |
| 3276 | Orleans Exploration Co., Inc. | | Oil & Gas Operator | Aug 1990 |
| 3277 | Orx Resources, Inc. | | Oil & Gas Operator | Dec 2009 |
| 3278 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | May 2024 |
| 3279 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 3280 | Osr Oil & Gas Corp | Midland, TX 79710 | Oil & Gas Operator | Dec 2023 |
| 3281 | Osyka Permian, LLC | Houston, TX 77079 | Oil & Gas Operator | May 2024 |
| 3282 | Otis C. Coles, Jr. | | Oil & Gas Operator | Jan 1998 |
| 3283 | Ouida Oil Co. | | Oil & Gas Operator | Apr 1999 |
| 3284 | Output Acquisition Corp. | | Oil & Gas Operator | Jul 2010 |
| 3285 | Owen Production Co | | Oil Operator | May 2001 |
| 3286 | Owl Creek Production Co., Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2006 |
| 3287 | Oxbow EP LLC | | Oil Operator | Dec 2023 |
| 3288 | Oxford Exploration Company | Denver, CO 80237 | Oil & Gas Operator | Aug 1995 |
| 3289 | Oxtex Inc | | Oil & Gas Operator | Oct 1989 |
| 3290 | Oxy Petroleum Inc | | Oil & Gas Operator | Jan 1986 |
| 3291 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | May 2024 |
| 3292 | Ozark Production Company, Inc. | | Oil & Gas Operator | Jan 2024 |
| 3293 | P & A Oilfield Services, Inc. | | Oil & Gas Operator | Jan 1998 |
| 3294 | P & A Well Service | | Oil & Gas Operator | Jan 1994 |
| 3295 | P & P Producing Inc | Midland, TX 79702 | Oil & Gas Operator | Feb 2015 |
| 3296 | P D Parker | | Oil & Gas Operator | Aug 1985 |
| 3297 | P. B. Operating Company | | Oil & Gas Operator | Feb 1978 |
| 3298 | P. K. Smith | | Oil Operator | Mar 1997 |
| 3299 | P. S. & G., Incorporated | | Gas Operator | Aug 1983 |
| 3300 | P.C.S.I. | | Oil & Gas Operator | Jun 1987 |