| 21401 | Opdycke Lease Partners, A General Partnership | Russell, KS 67665 | Oil Operator | Jun 2025 |
| 21402 | Opef Partnership, A General Partnership | Overland Park, KS 66221 | Oil Operator | Dec 2011 |
| 21403 | Open Door Holdings Inc | Surprise, AZ 85387-2015 | Oil & Gas Operator | Feb 2024 |
| 21404 | Open Door Productions Inc | Muskogee, OK 74401-1032 | Oil & Gas Operator | Apr 2020 |
| 21405 | Open Flow Gas Supply Corp | Du Bois, PA 15801-2442 | Oil & Gas Operator | Dec 2024 |
| 21406 | Open Range Energy LLC | Jones, OK 73049-8744 | Oil & Gas Operator | Mar 2025 |
| 21407 | Operating Engineers Local 17 Training Fund | Lake VIew, NY 14085 | Gas Operator | Dec 2024 |
| 21408 | Operator Unknown | Charleston, WV 25304-0000 | Oil & Gas Operator | Dec 2021 |
| 21409 | Opes Production Inc | Buffalo, WY 82834 | Gas Operator | Mar 2015 |
| 21410 | Opex Energy, LLC | Houston, TX 77042 | Oil & Gas Operator | Mar 2008 |
| 21411 | Opmi Operating Company | Houston, TX 77057 | Oil & Gas Operator | Jun 2008 |
| 21412 | Ops Group Limited | Houston, TX 77060 | Oil & Gas Operator | Jun 2014 |
| 21413 | Optima Conservation Resources Exploration LLC | | Oil & Gas Operator | Oct 2025 |
| 21414 | Optima Exploration LLC | Tulsa, OK 74116-5664 | Oil & Gas Operator | Mar 2015 |
| 21415 | Optimistic Oil Co. | | Oil & Gas Operator | Dec 1991 |
| 21416 | Optimum Exploration LLC | Dallas, TX 75254 | Oil & Gas Operator | Dec 2025 |
| 21417 | Opubco Resources Of TX Inc | Dallas, TX 75231 | Oil & Gas Operator | Sep 2005 |
| 21418 | Ora Oil Company | | Oil & Gas Operator | May 2017 |
| 21419 | Oracle Oil, LLC | | Oil & Gas Operator | Jul 2013 |
| 21420 | Oracle Resources Oklahoma LP | Dallas, TX 75240-5751 | Oil & Gas Operator | Feb 2008 |
| 21421 | Orange Petroleum Co. | Orangefield, TX 77639 | Oil & Gas Operator | May 1995 |
| 21422 | Orangefield East Corp | Dallas, TX 75382 | Oil Operator | Dec 2025 |
| 21423 | Orangefield Operating Corporation | Dallas, TX 75382 | Oil Operator | Dec 2025 |
| 21424 | Orason Resources Inc | Tulsa, OK 74169-1225 | Oil & Gas Operator | Nov 2006 |
| 21425 | Orb Exploration, L.L.C. | | Oil & Gas Operator | Jun 2017 |
| 21426 | Orbis Energy, L.L.C. | Austin, TX 78746 | Oil & Gas Operator | Oct 2001 |
| 21427 | Orbit Crude, Inc. | Midland, TX 79710 | Oil & Gas Operator | Dec 2025 |
| 21428 | Orbit Enterprises, Inc. | Lovington, NM 88260 | Oil & Gas Operator | Mar 2015 |
| 21429 | Orbit Gas Transmission, Inc | Owensboro, KY 42303 | Oil & Gas Operator | Dec 2023 |
| 21430 | Orbit Petroleum, Inc. | Irving, TX 75038 | Oil & Gas Operator | Sep 2010 |
| 21431 | Orbitron Operating Corp. | Fort Worth, TX 76102 | Oil & Gas Operator | Dec 1995 |
| 21432 | Orbrie Luman | Odessa, TX 79761 | Oil & Gas Operator | Jul 2025 |
| 21433 | Orca Operating Company LLC | Houston, TX 77056 | Oil & Gas Operator | Oct 2025 |
| 21434 | Oren Stone | Erick, OK 73645-4542 | Gas Operator | Jun 2022 |
| 21435 | Oretta Holdings LLC | Houston, TX 77010 | Oil & Gas Operator | Dec 2025 |
| 21436 | Organic Energy Company LLC | | Oil & Gas Operator | Oct 2025 |
| 21437 | Origin Prod Co Gonzales Prop LLC | New Braunfels, TX 78132 | Oil & Gas Operator | Dec 2025 |
| 21438 | Origin Production Company, Inc. | New Braunfels, TX 78132 | Oil & Gas Operator | Dec 2025 |
| 21439 | Origin Production Group LLC | Luling, TX 78648 | Oil Operator | Dec 2025 |
| 21440 | Oringderff, Alma Oil Properties | Dallas, TX 75225 | Oil & Gas Operator | Mar 2012 |
| 21441 | Oriole Operating LLC | Wichita Falls, TX 76308 | Oil Operator | Dec 2025 |
| 21442 | Orion Energen Inc. | Austin, TX 78731 | Oil & Gas Operator | Jul 2023 |
| 21443 | Orion Energy Corp | MT Vernon, IL 62864 | Oil & Gas Operator | Dec 1984 |
| 21444 | Orion Energy Partners LP | Denver, CO 80202 | Oil & Gas Operator | Nov 2010 |
| 21445 | Orion Exploration LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Apr 2015 |
| 21446 | Orion Exploration Partners LLC | Tulsa, OK 74105-5153 | Oil & Gas Operator | Oct 2025 |
| 21447 | Orion Oil & Gas Prop | Roswell, NM 88202 | Oil & Gas Operator | Apr 1998 |
| 21448 | Orion Oil & Gas Properties | Amarillo, TX 79109 | Gas Operator | Oct 2000 |
| 21449 | Orion Oil & Gas, LLC | Houston, TX 77042 | Oil & Gas Operator | Oct 2007 |
| 21450 | Orion Oil And Gas Corporation | Houston, TX 77082 | Oil & Gas Operator | Dec 2025 |
| 21451 | Orion Petro Corp | MT Vernon, IL 62864 | Oil & Gas Operator | Dec 2016 |
| 21452 | Orisol Oil Co. | Houston, TX 77206 | Oil Operator | Jun 2000 |
| 21453 | Orla Petco Inc & Hopi Drilling Co | Midland, TX 79702 | Oil Operator | Sep 2004 |
| 21454 | Orla Petco, Inc. | Midland, TX 79708 | Oil & Gas Operator | Dec 2025 |
| 21455 | Orland Oil & Gas LLC | FT Lauderdale, FL 33305 | Oil Operator | Aug 2024 |
| 21456 | Orleans Exploration Co., Inc. | | Oil & Gas Operator | Aug 1990 |
| 21457 | Orloski John C | Bartlesville, OK 74006 | Oil & Gas Operator | Jun 2025 |
| 21458 | Ormand, Don R. | Midland, TX 79705 | Oil & Gas Operator | Jan 2016 |
| 21459 | Oro Negro Inc. | | Oil & Gas Operator | Dec 2004 |
| 21460 | Oro Resources, LLC | Houston, TX 77024 | Oil & Gas Operator | Dec 2025 |
| 21461 | Orr Production Company | Austin, TX 78746 | Oil & Gas Operator | Dec 2000 |
| 21462 | Orr Robert W Jr | Zanesville, OH 43702-2683 | Oil & Gas Operator | Dec 2023 |
| 21463 | Orr, Jr., Donald R. | Batavia, NY 14020 | Gas Operator | Dec 2024 |
| 21464 | Orr, Robert M. | Monahans, TX 79756 | Oil & Gas Operator | Oct 1998 |
| 21465 | Orsburn, Wade Inc. | Gainesville, TX 76240 | Oil & Gas Operator | Nov 2002 |
| 21466 | Orson Leasing & Supply | Rockdale, TX 76567 | Oil & Gas Operator | Dec 2006 |
| 21467 | Orth Oil Company, Inc. | Cisco, TX 76437 | Oil & Gas Operator | Dec 2025 |
| 21468 | Orville S Slaughter Jr | Denver, CO 80205 | Oil & Gas Operator | Aug 2000 |
| 21469 | Orwig Oil Company Inc | Bradenton, FL 34212 | Oil & Gas Operator | Dec 2022 |
| 21470 | Orx Resources, Inc. | | Oil & Gas Operator | Dec 2009 |
| 21471 | Orx Resources, L.L.C. | Houston, TX 77067 | Oil & Gas Operator | Dec 2025 |
| 21472 | Oryx Energy Comp | | Oil & Gas Operator | Apr 1991 |
| 21473 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 21474 | Os&S Operating Inc. | Electra, TX 76360 | Oil & Gas Operator | Dec 2025 |
| 21475 | Osa Oil & Gas LLC | Tulsa, OK 74131 | Oil & Gas Operator | Aug 2023 |
| 21476 | Osage Energy Resources LLC | Bartlesville, OK 74005-2527 | Oil & Gas Operator | Aug 2025 |
| 21477 | Osage Energy, LLC | Colony, KS 66015 | Oil Operator | Nov 2023 |
| 21478 | Osage Exploration & Development Inc | San Diego, CA 92131-3807 | Oil & Gas Operator | Oct 2016 |
| 21479 | Osage Hot Oil Service | Newcastle, WY 82701 | Oil & Gas Operator | Jul 1997 |
| 21480 | Osage Oil & Transportation Inc | Cleveland, OK 74020 | Oil & Gas Operator | Nov 2000 |
| 21481 | Osage Operating Company LLC | Seattle, WA 98133 | Oil Operator | May 2006 |
| 21482 | Osage Partners LLC | | Oil & Gas Operator | Oct 2025 |
| 21483 | Osage Petroleum Corporation | Saint Louis, MO 63131-4691 | Oil & Gas Operator | Mar 2009 |
| 21484 | Osage Resources, LLC | Wichita, KS 67202 | Oil & Gas Operator | May 2025 |
| 21485 | Osair Inc | Mentor, OH 44061 | Oil & Gas Operator | Dec 2021 |
| 21486 | Osborn Energy, LLC | Bucyrus, KS 66013 | Oil & Gas Operator | Jul 2017 |
| 21487 | Osborn Heirs Co | San Antonio, TX 78217 | Oil & Gas Operator | Oct 2025 |
| 21488 | Osborn Heirs Com | | Oil & Gas Operator | May 1995 |
| 21489 | Osborn Heirs Company LTD | San Antonio, TX 78217 | Oil & Gas Operator | Jun 2025 |
| 21490 | Osborn Oil & Gas | | Oil & Gas Operator | Jun 1991 |
| 21491 | Osborn,W.B. Oil & Gas Operations | San Antonio, TX 78217 | Oil & Gas Operator | Dec 2025 |
| 21492 | Osborne Oil Co. | Dallas, TX 75244 | Oil & Gas Operator | Aug 2003 |
| 21493 | Osburn Gerald Dba Ozzy & Son Oil & Gas | Drumright, OK 74030-5467 | Oil Operator | Oct 2020 |
| 21494 | Oscar Oil Company | Iowa Park, TX 76367 | Oil & Gas Operator | Sep 2004 |
| 21495 | Oscar'S Well Service Inc | Okemah, OK 74859 | Oil & Gas Operator | Apr 1998 |
| 21496 | Osceola Oil & Gas Corporation | Somerset, TX 78069 | Oil & Gas Operator | Aug 1994 |
| 21497 | Osci Oil And Gas, Inc. | Parker, KS 66072 | Oil Operator | Jun 1998 |
| 21498 | Oshtah Oil Company LLC | Stratford, OK 74872 | Oil & Gas Operator | Sep 2018 |
| 21499 | Osman Global Services LLC | | Oil & Gas Operator | Jan 2025 |
| 21500 | Oso Exploration & Production, LLC | Houston, TX 77269 | Oil Operator | Dec 2025 |