| 501 | Forcenergy Inc | Miami, FL 33129 | Oil & Gas Operator | Mar 2015 |
| 502 | Forcenergy Onshore Inc. | Houston, TX 77002 | Oil & Gas Operator | Dec 2012 |
| 503 | Foree R L | Dallas, TX 75225 | Oil & Gas Operator | Aug 2001 |
| 504 | Foreland Resources LLC | Lakewood, CO 80228 | Oil & Gas Operator | Apr 2025 |
| 505 | Forest Oil Permian Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2015 |
| 506 | Forestar Petroleum Corporation | Denver, CO 80202 | Oil & Gas Operator | May 2017 |
| 507 | Fossil Creek Resources LLC | Arlington, TX 76011-5597 | Oil & Gas Operator | Mar 2015 |
| 508 | Fossil Energy Inc | Austin, TX 78746 | Oil & Gas Operator | Jul 2025 |
| 509 | Foundation Energy Managment LLC | Addison, TX 74119 | Oil & Gas Operator | May 2025 |
| 510 | Four-A Energy LLC | Cody, WY 82414 | Oil Operator | Jun 2025 |
| 511 | Frank Louis L | Kingsville, TX 78364 | Oil & Gas Operator | Aug 2003 |
| 512 | Fremont Energy Corporation | Oklahoma City, OK 73112 | Oil & Gas Operator | Dec 2004 |
| 513 | Frickey Investment MGT Co LLC | Lakewood, CO 80215 | Oil & Gas Operator | May 2025 |
| 514 | Fruehauf LLC | Gaylord, MI 49735 | Oil Operator | Feb 2005 |
| 515 | Fuel Exploration Inc | Denver, CO 80295 | Oil & Gas Operator | Jan 1992 |
| 516 | Fuel Resources Development Co | Denver, CO 80202 | Oil & Gas Operator | Feb 1994 |
| 517 | G & H Production Company LLC | Denver, CO 80202 | Oil Operator | Jan 2008 |
| 518 | G & H Resources LLC | Denver, CO 80202 | Oil & Gas Operator | Dec 2009 |
| 519 | Galaxy Oil Company | Wichita Falls, TX 76307 | Oil & Gas Operator | Mar 2015 |
| 520 | Gallagher Drilling Inc | Evansville, IN 47730 | Oil Operator | Dec 2020 |
| 521 | Gallagher T P | Boulder, CO 80303 | Oil Operator | Apr 2019 |
| 522 | Gary-Williams Production Company | Denver, CO 80202 | Oil & Gas Operator | May 2000 |
| 523 | Gas Ventures LLC | Thermopolis, WY 82443 | Oil & Gas Operator | Oct 2020 |
| 524 | Gasamat Oil Corp Of Colorado | Boulder, CO 80303 | Oil Operator | Jun 2025 |
| 525 | Gasco Inc | | Oil & Gas Operator | Jun 1998 |
| 526 | Gasco Production Company | Denver, CO 80237 | Oil & Gas Operator | Dec 2015 |
| 527 | General American Oil Co Of Texas | | Oil & Gas Operator | Mar 1983 |
| 528 | General Atlantic Resources Inc | Denver, CO 80202 | Oil & Gas Operator | Jan 2022 |
| 529 | General Crude Oil Co | Houston, TX 77005 | Oil & Gas Operator | Dec 1979 |
| 530 | General Oil Company, Inc. | Wichita, KS 67213 | Oil & Gas Operator | Jul 2025 |
| 531 | Genesis Production Company | | Oil & Gas Operator | May 1991 |
| 532 | Genesis St Operating LLC | Kansas City, MO 64108 | Oil & Gas Operator | Jul 2025 |
| 533 | Geodyne Operating Company | Tulsa, OK 74103 | Oil & Gas Operator | Jun 2015 |
| 534 | Germany Operating Company | Houston, TX 77090 | Oil & Gas Operator | Sep 2011 |
| 535 | Getty Oil Company | Hays, KS 67601 | Oil & Gas Operator | Mar 2015 |
| 536 | Gibbs William | | Oil Operator | Feb 2000 |
| 537 | Gibson J W | | Oil & Gas Operator | Sep 1999 |
| 538 | Gilmore Oil & Gas | Houston, TX 77002 | Oil & Gas Operator | Jul 2025 |
| 539 | Girouard Richard L | | Oil Operator | May 1985 |
| 540 | GKM Inc | | Oil & Gas Operator | Mar 1990 |
| 541 | Glenmar Company | Monterey, CO 93940 | Oil Operator | Oct 1998 |
| 542 | GLG Energy LP | Austin, TX 78701 | Oil & Gas Operator | Jun 1994 |
| 543 | GMT Energy Corporation | Houston, TX 77042 | Oil & Gas Operator | Feb 2005 |
| 544 | GMT Exploration Company LLC | Denver, CO 80202 | Oil & Gas Operator | May 2025 |
| 545 | Golden Energy Partners LLC | Denver, CO 80202 | Oil & Gas Operator | Jan 2010 |
| 546 | Golden Eye Resources LLC | Greenwood VLG, CO 80121 | Oil Operator | Mar 2014 |
| 547 | Goldmark Engineering Inc | Casper, WY 82602 | Oil & Gas Operator | Oct 2004 |
| 548 | Goodstein Fred | Casper, WY 82602 | Oil & Gas Operator | Mar 1984 |
| 549 | Gorman Construction LLC | Gillette, WY 82716 | Oil Operator | May 2025 |
| 550 | Gould Joseph B | Las Vegas, NV 89101 | Oil & Gas Operator | Apr 2001 |
| 551 | Gpo Operations LLC | Labarge, WY 83123 | Oil & Gas Operator | Jun 2025 |
| 552 | Grace Petroleum Corp. | Tulsa, OK 74103 | Oil & Gas Operator | Oct 1997 |
| 553 | Graham Royalty LTD | Covington, LA 70434 | Oil & Gas Operator | Jul 2007 |
| 554 | Granite Creek Energy LLC | Cody, WY 82414 | Oil & Gas Operator | May 2025 |
| 555 | Grayhorse Operating Inc | Tulsa, OK 74103-4439 | Oil & Gas Operator | Apr 2025 |
| 556 | Grayling Resources LTD | Lakewood, CO 80235 | Oil & Gas Operator | Jul 2020 |
| 557 | Grayson Mill Operating LLC | Houston, TX 77024 | Oil & Gas Operator | May 2025 |
| 558 | GRB Resources | Tulsa, OK 74103 | Oil & Gas Operator | Mar 2004 |
| 559 | Great Northern Drilling Company | Billings, MT 59103 | Oil & Gas Operator | Jun 2016 |
| 560 | Great Northern Gas Company | Denver, CO 80293-0602 | Oil & Gas Operator | Jul 2017 |
| 561 | Great Western Drilling Co | Midland, TX 79701 | Oil & Gas Operator | Jul 2025 |
| 562 | Great Western Oil Company | | Oil & Gas Operator | Dec 1984 |
| 563 | Great Western Resources Inc | | Oil & Gas Operator | Dec 1989 |
| 564 | Green Reserve Energy Holdings LLC | Houston, TX 77077 | Oil & Gas Operator | Jun 2025 |
| 565 | Greenstreet Lloyd | | Oil Operator | Dec 1986 |
| 566 | Greenwood Resources | | Oil & Gas Operator | Jan 1992 |
| 567 | Greka Am Inc | Santa Maria, CA 93454 | Oil & Gas Operator | May 2013 |
| 568 | Grey Hawk Operating LLC | Birmingham, AL 35242 | Oil Operator | Jan 2024 |
| 569 | Greylock Production LLC | Charleston, WV 25311-1264 | Oil & Gas Operator | May 2025 |
| 570 | Griffiths Oil LLC | Edgerton, WY 82635 | Oil Operator | May 2025 |
| 571 | Grizzly Operating LLC | Houston, TX 77057 | Oil & Gas Operator | May 2025 |
| 572 | GRMR Oil And Gas LLC | Broomfield, CO 80021 | Oil & Gas Operator | Jun 2025 |
| 573 | Gross Todd | Pine Bluffs, WY 82082 | Oil & Gas Operator | Mar 2007 |
| 574 | Grynberg Petroleum Company | Greenwood Vge, CO 80111-3326 | Oil & Gas Operator | Oct 2019 |
| 575 | Grynberg, Jack J. | Denver, CO 80237 | Oil & Gas Operator | Jun 2021 |
| 576 | Guenthart William & Lavonne | Newcastle, WY 82701 | Oil Operator | Apr 2025 |
| 577 | Gulf Energy Corporation | Denver, CO 80237 | Oil & Gas Operator | Jun 1987 |
| 578 | Gulf Exploration, LLC | Oklahoma City, OK 73114 | Oil & Gas Operator | Jun 2025 |
| 579 | Gulf Oil Corp. | Denver, CO 80201-0599 | Oil & Gas Operator | Dec 2014 |
| 580 | Gulf Production Corporation | Oklahoma City, OK 73114 | Oil & Gas Operator | Apr 2015 |
| 581 | H & H Star Energy Inc | Traverse City, MI 49684 | Oil & Gas Operator | Aug 2016 |
| 582 | H & M Oil Producers | Littleton, CO 80160 | Oil & Gas Operator | Apr 2000 |
| 583 | H & R Oil Company | | Oil & Gas Operator | Dec 2000 |
| 584 | H & R Well Services, Inc. | FT Morgan, CO 80701 | Oil & Gas Operator | Apr 2015 |
| 585 | H C M Energy LLC | Billings, MT 59102 | Oil Operator | Jul 2003 |
| 586 | H D Oil Company | Thermopolis, WY 82443 | Oil Operator | Jun 2025 |
| 587 | H G H Oil Company | | Oil Operator | Dec 1990 |
| 588 | H2oil Services LLC | | Oil Operator | Jun 2025 |
| 589 | Hadley/Jackson Energy LLC | Lake Forest, IL 60045 | Oil & Gas Operator | May 2025 |
| 590 | Hadson Petroleum Corporation | Oklahoma City, OK 73102 | Oil & Gas Operator | Mar 2015 |
| 591 | Hallador Petroleum LLP | Denver, CO 80264 | Oil & Gas Operator | Feb 2019 |
| 592 | Hallwood Petroleum | Denver, CO 80237 | Oil & Gas Operator | Dec 1997 |
| 593 | Hamon Jake L | Dallas, TX 75201-3902 | Oil & Gas Operator | Nov 1997 |
| 594 | Hanson Operating Company Inc | Roswell, NM 88202 | Oil & Gas Operator | Apr 2025 |
| 595 | Harpel John P Jr | FT. Collins, CO 80525 | Oil & Gas Operator | May 1998 |
| 596 | Harper Oil Co. | Denver, CO 80217 | Oil & Gas Operator | Mar 2025 |
| 597 | Harrell Oil Company LLC | Ardmore, OK 73402 | Oil Operator | Jan 2025 |
| 598 | Harvey E Yates Company | Roswell, NM 88202 | Oil & Gas Operator | Feb 2015 |
| 599 | Haug Lawrence | Kimball, NE 69145 | Oil & Gas Operator | Jul 2007 |
| 600 | Havoco Inc | Newcastle, WY 82701 | Oil & Gas Operator | Aug 2005 |