| 501 | Great Plains Exploration LLC | Mentor, OH 44060 | Oil & Gas Operator | Dec 2016 |
| 502 | Green Energy Inc | Wooster, OH 44691 | Oil & Gas Operator | Dec 2024 |
| 503 | Green Gas Co | Wooster, OH 44691 | Oil & Gas Operator | Dec 2020 |
| 504 | Greenbrier Energy Inc | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 505 | Greenland Petroleum Co | Belle Valley, OH 43717 | Oil & Gas Operator | Dec 1991 |
| 506 | Greenwood James W | New Matamoras, OH 45767 | Oil & Gas Operator | Dec 2014 |
| 507 | Greenwood Oil LLC | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 508 | Gregg Price Corp | Dover, OH 44622 | Oil & Gas Operator | Dec 2014 |
| 509 | Gress Oil & Gas | Coshocton, OH 43812 | Oil & Gas Operator | Dec 2024 |
| 510 | Grim Paul A | Logan, OH 43138-9445 | Oil & Gas Operator | Dec 2020 |
| 511 | Grimsby Exploration Inc | Canton, OH 44709 | Oil & Gas Operator | Dec 2018 |
| 512 | Group Maintenance Corp | Jefferson, OH 44047 | Oil & Gas Operator | Dec 2012 |
| 513 | Guardian Management Inc | Marion, OH 43302 | Oil & Gas Operator | Dec 1997 |
| 514 | Guernsey Petroleum Corporation | Atlanta, GA 30318 | Oil & Gas Operator | Nov 1997 |
| 515 | Gulfport Appalachia LLC | Oklahoma City, OK 73114-2640 | Oil & Gas Operator | Jun 2025 |
| 516 | Gulfport Energy Corporation | Oklahoma City, OK 73114-5003 | Oil & Gas Operator | Feb 2025 |
| 517 | GWB Oil & Gas LLC | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 518 | H & A Drilling | Newark, OH 43056 | Oil Operator | Dec 2024 |
| 519 | H & D Drilling Co Inc | Frazeysburg, OH 43822 | Oil & Gas Operator | Dec 2024 |
| 520 | H & H Energy Of Ohio LTD | Zanesville, OH 43701 | Oil & Gas Operator | Dec 2024 |
| 521 | H & K Energy Corp | Columbus, OH 43229 | Oil & Gas Operator | Dec 1991 |
| 522 | H & S Drilling Co Inc | Frazeysburg, OH 43822 | Oil & Gas Operator | Dec 2016 |
| 523 | H & S Operating Co., Inc. | Winesburg, OH 44690 | Oil & Gas Operator | Dec 2024 |
| 524 | H & W Drilling Inc | Racine, OH 45769 | Oil & Gas Operator | Dec 2023 |
| 525 | H & W Energy | Youngstown, OH 44512 | Oil & Gas Operator | Dec 2015 |
| 526 | H I Smith Oil & Gas Inc | Holmesville, OH 44633 | Oil & Gas Operator | Dec 2024 |
| 527 | H L Altier Service Co Inc | Canton, OH 44718-3752 | Oil & Gas Operator | Dec 2013 |
| 528 | H. C. Oil Co. | Weatherford, TX 76085 | Oil & Gas Operator | Sep 2025 |
| 529 | Haddad & Brooks Inc | Washington, PA 15301 | Oil & Gas Operator | Dec 2018 |
| 530 | Haessly Hardwood Lumber Inc | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 531 | Halcon Operating Co., Inc. | Houston, TX 77024 | Oil & Gas Operator | Sep 2025 |
| 532 | Hall & Horning Serv Inc | Atwater, OH 44201-9375 | Oil & Gas Operator | Dec 2009 |
| 533 | Hall Drilling LLC (Oil & Gas) | Ellenboro, WV 26346 | Gas Operator | Sep 2014 |
| 534 | Hall Energy Inc | Magnetic Spring, OH 43036 | Oil & Gas Operator | Dec 2017 |
| 535 | Hall IVan & Assoc Inc | Berea, OH 44017 | Oil & Gas Operator | Dec 1997 |
| 536 | Hall Thomas E | Marietta, OH 45750 | Oil & Gas Operator | Dec 2021 |
| 537 | Halter Ralph P | Robertsville, OH 44670 | Oil Operator | Dec 1999 |
| 538 | Hamblin Ralph Inc | MT Vernon, OH 43050 | Oil & Gas Operator | Dec 1991 |
| 539 | Hamilton Leonard O | Marietta, OH 45750 | Oil & Gas Operator | Dec 2024 |
| 540 | Hanna M A Co | Cleveland, OH 44114-1824 | Oil & Gas Operator | Dec 1991 |
| 541 | Hardco, Inc. | Cleveland, OH 44115 | Oil & Gas Operator | Dec 1992 |
| 542 | Hardesty Production | Gambier, OH 43022 | Oil & Gas Operator | Dec 2024 |
| 543 | Hardin Hanley E | Zanesville, OH 43701 | Oil & Gas Operator | Dec 1995 |
| 544 | Harley Drilling & Producing LTD | Burbank, OH 44214 | Oil & Gas Operator | Dec 2024 |
| 545 | Harmon O G LLC | Graysville, OH 45734 | Oil & Gas Operator | Dec 2024 |
| 546 | Harmons Well Service | Graysville, OH 45734 | Oil & Gas Operator | Dec 2019 |
| 547 | Harnetty Francis Dba Harnetty Oil & Gas | Junction City, OH 43748 | Oil & Gas Operator | Dec 2019 |
| 548 | Harris Engineering Co | Dallas, TX 75248 | Oil & Gas Operator | Dec 1996 |
| 549 | Harrison Energy | Tippecanoe, OH 44699 | Oil & Gas Operator | Dec 2000 |
| 550 | Hatco Productions LTD | North Augusta, SC 29860 | Oil Operator | Dec 2024 |
| 551 | Hawke Inc | Barbertib, OH 44203 | Oil & Gas Operator | Dec 2024 |
| 552 | Hayes James Brent | Guysville, OH 45735-9496 | Oil & Gas Operator | Dec 2024 |
| 553 | Headington Oil Company, L.P. | Dallas, TX 75231 | Oil & Gas Operator | Mar 2008 |
| 554 | Hearn Oil Co. LLC | Newport, OH 45768 | Oil & Gas Operator | Dec 2023 |
| 555 | Heat Controller Inc | Jackson, MI 49204 | Oil & Gas Operator | Dec 1996 |
| 556 | Hehns Quality Gardens Inc | Wadsworth, OH 44281 | Oil & Gas Operator | Dec 2024 |
| 557 | Heinrich Enterprises Inc Dba Washington Operations | Reno, OH 45773 | Oil & Gas Operator | Dec 2024 |
| 558 | Helms Oil | Brinkhaven, OH 43006 | Oil Operator | Dec 2018 |
| 559 | Herald Oil & Gas Co | Middleport, OH 45760-9000 | Oil & Gas Operator | Dec 2010 |
| 560 | Hess Ohio Developments LLC | Houston, TX 77010 | Oil & Gas Operator | Sep 2018 |
| 561 | Hess Ohio Resources LLC | Houston, TX 77010 | Oil & Gas Operator | Jun 2014 |
| 562 | HG Energy LLC | Parkersburg, WV 26101 | Oil & Gas Operator | Dec 2021 |
| 563 | Hi Snyder/Snyder Oil & Gas Inc | Dover, OH 44622 | Oil & Gas Operator | Dec 2019 |
| 564 | High Plains Gas Systems, Inc. | Houston, TX 77019 | Oil & Gas Operator | Sep 2025 |
| 565 | Highman Oil & Gas LLC | Woodsfield, OH 43793 | Oil & Gas Operator | Dec 2024 |
| 566 | Hilcorp Energy Company | Houston, TX 77208 | Oil & Gas Operator | Sep 2025 |
| 567 | Hill Drilling Inc | Millersburg, OH 44654 | Oil & Gas Operator | Dec 1997 |
| 568 | Hill William F | Millersburg, OH 44654 | Oil & Gas Operator | Dec 1993 |
| 569 | Hilltop Development Corp | Frazeysburg, OH 43822 | Oil & Gas Operator | Dec 1984 |
| 570 | HLH Drilling Inc | Andover, OH 44003 | Oil & Gas Operator | Dec 1985 |
| 571 | Hocking Hills Energy And Well Service LLC | Logan, OH 43138-8497 | Oil & Gas Operator | Dec 2024 |
| 572 | Hocking Technical College | Nelsonville, OH 45764 | Oil & Gas Operator | Dec 2024 |
| 573 | Holbrook LLC | Bimble, KY 40915 | Oil & Gas Operator | Jun 2025 |
| 574 | Holl Investment Co | Logan, OH 43138 | Oil & Gas Operator | Dec 2019 |
| 575 | Hoover Frank W Dba Cherokee Drilling | Miramar Beach, FL 32550 | Oil & Gas Operator | Dec 2024 |
| 576 | Hoover Producing & Operating | Newark, OH 43055 | Oil & Gas Operator | Dec 2001 |
| 577 | Hopco Resources Inc | Columbus, OH 43065 | Oil & Gas Operator | Dec 2024 |
| 578 | Hopewell Oil & Gas Development Company | Columbus, OH 43228 | Oil & Gas Operator | Dec 2019 |
| 579 | Hortin & Huffman Pet Geol | Worthington, OH 43085 | Oil & Gas Operator | Dec 2000 |
| 580 | Hottel Glenn D | W Salem, OH 44287 | Oil & Gas Operator | Dec 1993 |
| 581 | Hottel Oil & Gas LLC | Wooster, OH 44691-7639 | Oil & Gas Operator | Dec 2013 |
| 582 | Houghton Investments LLC | Columbus, OH 43235 | Oil & Gas Operator | Dec 2024 |
| 583 | Hounds Oil & Gas LLC | Carbon Hill, OH 43111 | Oil & Gas Operator | Dec 2024 |
| 584 | Householder Oil Co | Junction City, OH 43748 | Oil & Gas Operator | Dec 1988 |
| 585 | Howdyshell Pumping Inc | Logan, OH 43138 | Oil Operator | Dec 2024 |
| 586 | Howells Oil & Gas | Graysville, OH 45734 | Oil & Gas Operator | Dec 2024 |
| 587 | Huffman-Bowers Inc | New Lexington, OH 43764 | Oil & Gas Operator | Dec 2024 |
| 588 | Hydrocarbon Resources LTD | Medina, OH 44256 | Oil & Gas Operator | Dec 2022 |
| 589 | Independent Oil Investors | Lakeside, MI 49116 | Oil & Gas Operator | Dec 1992 |
| 590 | Indian Hills Resources LLC | Williamsburg, MI 49690 | Oil & Gas Operator | Dec 2024 |
| 591 | Industry Standard Supplies Inc | Dover, OH 44622 | Oil & Gas Operator | Dec 2024 |
| 592 | Inland Drilling Co Inc | Garretsville, OH 44231 | Oil & Gas Operator | Dec 1992 |
| 593 | Inland Petroleum | Newark, OH 43055 | Oil Operator | Dec 2009 |
| 594 | Inr Ohio LLC | Morgantown, WV 26508-9209 | Oil & Gas Operator | Jun 2025 |
| 595 | Irvin Drilling Corp | Zanesville, OH 43701 | Oil & Gas Operator | Dec 1990 |
| 596 | J & C Oil | New Matamoras, OH 45767-6035 | Oil & Gas Operator | Dec 2024 |
| 597 | J & M Oil Co | Overland PK, KS 66209 | Oil & Gas Operator | May 2025 |
| 598 | J & S Oil Co | Graham, TX 76450 | Oil & Gas Operator | Apr 2022 |
| 599 | J & T Productions LLC | Tallmansville, WV 26237 | Oil & Gas Operator | Dec 2022 |
| 600 | J M Adams Roustabout & Pipeline Construction Inc. | New Concord, OH 43762 | Oil & Gas Operator | Dec 2024 |