| 20501 | Ohio Energy Assets, Inc. | Laurelville, OH 43135 | Oil & Gas Operator | Dec 2014 |
| 20502 | Ohio Energy Operators LLC | Colorado Spring, CO 80908 | Oil Operator | Dec 2018 |
| 20503 | Ohio Kentucky Oil Corporation | Lexington, KY 40503 | Oil & Gas Operator | Dec 2024 |
| 20504 | Ohio L & M Company Inc | Marietta, OH 45750 | Oil & Gas Operator | Dec 2008 |
| 20505 | Ohio Natural Fuel Co | Canton, OH 44718 | Oil & Gas Operator | Dec 1985 |
| 20506 | Ohio Oil & Gas | Fowler, OH 44418 | Oil & Gas Operator | Dec 1988 |
| 20507 | Ohio Production Corp | Westerville, OH 43081 | Oil & Gas Operator | Dec 2001 |
| 20508 | Ohio Production* | Newark, OH 43055 | Oil & Gas Operator | Dec 1987 |
| 20509 | Ohio Valley Energy Systems Corp | Austintown, OH 44515 | Oil & Gas Operator | Dec 2025 |
| 20510 | Ohio Valley Energy, Inc | Livermore, KY 42352 | Oil Operator | Dec 2023 |
| 20511 | Ohlhausen Oil Company | Abilene, TX 79608 | Oil & Gas Operator | Jun 2026 |
| 20512 | Oi Auburn, Inc. | Tulsa, OK 74135 | Gas Operator | Dec 2024 |
| 20513 | Oil & Gas Acquisition Group Inc | Austin, TX 78716 | Oil & Gas Operator | May 2003 |
| 20514 | Oil & Gas Development Company | | Oil & Gas Operator | May 1991 |
| 20515 | Oil & Gas Exploration Inc | Cleveland, OK 74020 | Oil & Gas Operator | Aug 2013 |
| 20516 | Oil & Gas MGMT Inc | Mount Pleasant, PA 15666-3304 | Oil & Gas Operator | Dec 2024 |
| 20517 | Oil & Gas Operations | Midland, TX 79706 | Oil & Gas Operator | Jun 2026 |
| 20518 | Oil & Gas Producers, Inc | Topeka, KS 66604 | Oil Operator | Jun 2004 |
| 20519 | Oil & Gas Properties | Midland, TX 79704 | Oil & Gas Operator | Jun 2026 |
| 20520 | Oil & Gas Property MGMT., Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 1996 |
| 20521 | Oil & Gas Servic | | Oil Operator | Jun 1983 |
| 20522 | Oil & Gas Solutions LTD | Wooster, OH 44691 | Oil & Gas Operator | Dec 2007 |
| 20523 | Oil & Gas SVC Inc | Reelsville, IN 46171-9686 | Gas Operator | Dec 1991 |
| 20524 | Oil & Realty Devlop Inc | Columbus, OH 43212 | Oil Operator | Dec 1986 |
| 20525 | Oil And Gas Futures, Inc. | | Oil & Gas Operator | May 1977 |
| 20526 | Oil And Gas Management, Inc. | Kansas City, MO 64106 | Oil Operator | Apr 2011 |
| 20527 | Oil Capital Corporation | Littleton, CO 80122 | Gas Operator | May 2009 |
| 20528 | Oil Capital Operating, LLC | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2026 |
| 20529 | Oil Center Operating Inc | Fort Worth, TX 76102-5108 | Oil & Gas Operator | Apr 2014 |
| 20530 | Oil Coast Corp. | S Houston, TX 77587 | Oil & Gas Operator | Jun 2026 |
| 20531 | Oil Company Of America, Inc. | Hays, KS 67601 | Oil Operator | Dec 2009 |
| 20532 | Oil Country Management, Inc. | | Oil & Gas Operator | Jan 2005 |
| 20533 | Oil Creek Operators LLC | Franklin, PA 16323 | Oil Operator | Dec 2025 |
| 20534 | Oil Creek Production Company | Prague, OK 74864-0667 | Oil & Gas Operator | Dec 2025 |
| 20535 | Oil Development Co | | Oil & Gas Operator | Jan 1979 |
| 20536 | Oil Drillers & D | | Oil & Gas Operator | Feb 1992 |
| 20537 | Oil Enterprises | Logan, OH 43138 | Oil & Gas Operator | Dec 2025 |
| 20538 | Oil Exploration Of America Inc | Sisseton, SD 57262-9503 | Oil & Gas Operator | Jun 2001 |
| 20539 | Oil Field Manage | | Oil Operator | Jun 1991 |
| 20540 | Oil Inc | | Oil & Gas Operator | Dec 1971 |
| 20541 | Oil Internationa | | Oil Operator | Jun 1986 |
| 20542 | Oil Investors Inc | Crescent, OK 73028 | Oil & Gas Operator | Mar 2026 |
| 20543 | Oil Lease Operating Co. | Coldspring, TX 77331 | Oil & Gas Operator | Aug 2003 |
| 20544 | Oil Lift Inc | Metairie, LA 70002 | Oil & Gas Operator | Apr 2020 |
| 20545 | Oil Management Corporation | Dallas, TX 75206 | Oil & Gas Operator | Apr 2022 |
| 20546 | Oil Mountain Energy Inc | Casper, WY 82609 | Oil Operator | Apr 2026 |
| 20547 | Oil Operations Inc | | Oil & Gas Operator | Apr 2011 |
| 20548 | Oil Operators Inc. | | Oil & Gas Operator | Nov 2024 |
| 20549 | Oil Palace, Inc. | | Oil Operator | Jun 2016 |
| 20550 | Oil Partners | Salina, KS 67401 | Oil Operator | Jun 2001 |
| 20551 | Oil Partners, LLC | Salina, KS 67401 | Oil Operator | Feb 2026 |
| 20552 | Oil Patch Energy LLC | Broken Arrow, OK 74014 | Oil & Gas Operator | Nov 2025 |
| 20553 | Oil Patch Operators Co., L.L.C. | Kilgore, TX 75663 | Oil & Gas Operator | Jun 2026 |
| 20554 | Oil Patch Operators, LLC | | Oil & Gas Operator | Jul 2005 |
| 20555 | Oil Pool Inc | Tulsa, OK 74132-2659 | Oil & Gas Operator | Mar 2026 |
| 20556 | Oil Producers In | | Oil & Gas Operator | Dec 1996 |
| 20557 | Oil Producers, Inc. Of Kansas | Wichita, KS 67206 | Oil & Gas Operator | Jun 2026 |
| 20558 | Oil Production Management Inc | Squaw Valley, CA 93675-9725 | Oil & Gas Operator | Dec 2002 |
| 20559 | Oil Production S | | Oil Operator | Sep 1993 |
| 20560 | Oil Production Systems Inc | Cushing, OK 74023 | Oil & Gas Operator | Jan 2013 |
| 20561 | Oil Projects, LLC | Houston, TX 77027 | Oil & Gas Operator | Jun 2026 |
| 20562 | Oil Prop Company | | Oil & Gas Operator | Sep 1995 |
| 20563 | Oil Prop Investm | | Oil Operator | Dec 1995 |
| 20564 | Oil Properties Co., Inc. | Wichita, KS 67208 | Gas Operator | Dec 2009 |
| 20565 | Oil Property Man | | Oil & Gas Operator | Jun 1995 |
| 20566 | Oil Property Management Inc | Attica, KS 67009 | Oil & Gas Operator | Feb 2021 |
| 20567 | Oil Recovery Systems Inc | Tulsa, OK 74145-4619 | Oil & Gas Operator | Feb 2026 |
| 20568 | Oil Recovery, Inc. | | Oil Operator | Sep 1992 |
| 20569 | Oil Reserves Corp Of America | | Oil & Gas Operator | May 2002 |
| 20570 | Oil Rock Oil Company, Inc. | Elizabeth, WV 26143 | Oil & Gas Operator | Dec 2021 |
| 20571 | Oil Rock Resources, LLC | Weatherford, TX 76088 | Oil & Gas Operator | Jan 2024 |
| 20572 | Oil Search (Alaska), LLC | | Oil & Gas Operator | Mar 2026 |
| 20573 | Oil Search Inc | Brookfield, OH 44403 | Oil & Gas Operator | Dec 2025 |
| 20574 | Oil Securities Inc. | | Gas Operator | Dec 2003 |
| 20575 | Oil State Petroleum Inc | Jennings, OK 74038 | Oil & Gas Operator | Mar 2026 |
| 20576 | Oil Tech Producers Corporation | Moundridge, KS 67107 | Gas Operator | Feb 2026 |
| 20577 | Oil Ventures LTD | | Oil & Gas Operator | Jan 2013 |
| 20578 | Oil Well Buyers Corp. | Houston, TX 77056 | Oil & Gas Operator | Dec 2024 |
| 20579 | Oil Well Management Co. | | Oil & Gas Operator | Dec 1989 |
| 20580 | Oil, Gas, Etc. LLC | Katy, TX 77449 | Oil & Gas Operator | Jun 2026 |
| 20581 | Oil,Gas & Other Minerals, Inc. | | Oil & Gas Operator | Apr 1996 |
| 20582 | Oil-Tech Prod Co | | Oil & Gas Operator | Oct 1992 |
| 20583 | Oil-X Corp., The | FT Stockton, TX 79735 | Oil & Gas Operator | Jun 2026 |
| 20584 | Oilbank Production LLC | Norman, OK 73072 | Oil Operator | Feb 2026 |
| 20585 | Oilco Energy Inc | Duncan, OK 73533 | Oil & Gas Operator | Mar 2015 |
| 20586 | Oildigger Resources Fund L LLLP | Billings, MT 59101 | Oil & Gas Operator | Apr 2026 |
| 20587 | Oilex Int'L Investments, Inc. | Luling, TX 78648 | Oil & Gas Operator | Jun 2026 |
| 20588 | Oilfield Consultants | | Oil & Gas Operator | Dec 1987 |
| 20589 | Oilfield Management, Inc. (A) | Midland, TX 79702 | Oil & Gas Operator | Jun 2026 |
| 20590 | Oilfield Operating Company | Cushing, OK 74023-1347 | Oil & Gas Operator | Jan 2018 |
| 20591 | Oilfield Research, Inc | | Oil Operator | Dec 2021 |
| 20592 | Oilfield Salvage & Service Company | Littleton, CO 80120 | Oil & Gas Operator | Mar 2026 |
| 20593 | Oilfield Search | | Oil Operator | Mar 1990 |
| 20594 | Oilfield Services And Supply Co. Inc. | | Oil Operator | Sep 1989 |
| 20595 | Oilfield Services, LLC | Winfield, KS 67156 | Oil Operator | Nov 2017 |
| 20596 | Oilfield Truck Service | | Oil Operator | Jun 2014 |
| 20597 | Oilrox Resources LLC | San Antonio, TX 78258 | Oil & Gas Operator | Feb 2026 |
| 20598 | Oilsearch Corporation | Albuquerque, NM 87109 | Oil & Gas Operator | Feb 1994 |
| 20599 | Oiltech Inc | Yuba City, CA 95991 | Oil & Gas Operator | Dec 1984 |
| 20600 | Oiltex, Inc. | Baltimore, MD 21221 | Oil & Gas Operator | Dec 2013 |