| 601 | Weiser-Brown Oil Co | Magnolia, AR 71754 | Oil Operator | Feb 2024 |
| 602 | Westhall Associates, Inc. | Corpus Chrsti, TX 78477 | Oil & Gas Operator | Aug 1997 |
| 603 | Westport Oil & Gas Company LP | The Woodlands, TX 77380 | Oil & Gas Operator | Feb 2007 |
| 604 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Apr 2024 |
| 605 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Apr 2024 |
| 606 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Feb 2024 |
| 607 | Whittier Operating Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2007 |
| 608 | Whittington Operating Company | Houston, TX 77069 | Oil & Gas Operator | Apr 2024 |
| 609 | Wilcox Operating Corporation | Shreveport, LA 71115 | Oil & Gas Operator | Apr 2024 |
| 610 | Wild Cat Operating Company | Victoria, TX 77903 | Oil & Gas Operator | Mar 2008 |
| 611 | Windrush Operating Co., L.L.C. | Longville, LA 70652 | Oil & Gas Operator | Apr 2024 |
| 612 | Wing Corporation | Houston, TX 77002 | Oil & Gas Operator | Jun 2000 |
| 613 | Wolf Energy | Midland, TX 79701 | Oil & Gas Operator | Jan 1995 |
| 614 | Wynn-Crosby Energy, Inc. | Houston, TX 77002 | Oil & Gas Operator | May 2005 |
| 615 | Wynn-Crosby Operating, LTD. | Dallas, TX 75201 | Oil & Gas Operator | Apr 2024 |
| 616 | Xeric Oil & Gas Corporation | Midland, TX 79702 | Oil & Gas Operator | Apr 2014 |
| 617 | Xplore Operating, LLC | Arlington, TX 76001 | Oil & Gas Operator | Apr 2024 |
| 618 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Apr 2024 |
| 619 | Yentzen Investments, Inc. | Sugar Land, TX 77478 | Oil Operator | May 1993 |
| 620 | Yuma E & P Company, Inc. | Houston, TX 77027 | Oil & Gas Operator | Apr 2024 |
| 621 | Yuma Petroleum Company | Houston, TX 77027 | Oil & Gas Operator | Aug 2002 |
| 622 | Zachry Exploration, Inc. | San Antonio, TX 78205 | Oil & Gas Operator | Apr 2024 |
| 623 | Zachry Exploration, LLC | San Antonio, TX 78224 | Oil & Gas Operator | Apr 2024 |
| 624 | Zachry Exploration, LTD. | San Antonio, TX 78205 | Oil & Gas Operator | Jan 2009 |
| 625 | Zebra Oil Company | El Campo, TX 77437 | Oil & Gas Operator | Apr 2024 |
| 626 | Zinke & Trumbo, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2007 |
| 627 | Zinn Petroleum Co. | Houston, TX 77024 | Oil & Gas Operator | Nov 2021 |