| 101 | Stellar Oil Company | Arvada, CO 80006 | Oil & Gas Operator | Dec 1998 |
| 102 | Stephens Production Company | The Woodlands, TX 77381 | Oil & Gas Operator | Jan 2024 |
| 103 | Sterling Energy Corporation | Denver, CO 80202 | Oil & Gas Operator | Sep 1995 |
| 104 | Stewart Petroleum Corporation | Greenwood VIllage, CO 80111 | Oil & Gas Operator | Dec 2023 |
| 105 | Stone & Wolf LLC | Sheridan, WY 82801 | Oil & Gas Operator | Dec 2006 |
| 106 | Stone Energy Corporation | Denver, CO 80202-2828 | Oil & Gas Operator | Oct 2014 |
| 107 | Stone Energy LLC | Denver, CO 80202 | Oil & Gas Operator | May 2005 |
| 108 | Stone Petroleum Corporation | | Oil & Gas Operator | Dec 1996 |
| 109 | Storm Cat Energy (USA) Operating Corporation | Denver, CO 80202 | Gas Operator | Jun 2017 |
| 110 | Stovall Oil Company | Casper, WY 82602 | Oil & Gas Operator | Aug 1998 |
| 111 | Strachan Exploration Inc | Englewood, CO 80112 | Oil & Gas Operator | Feb 2024 |
| 112 | Stringer E M | | Oil Operator | May 1996 |
| 113 | Stripper Oil Company Inc | | Oil Operator | Dec 2023 |
| 114 | Stroud Petroleum, Inc. | Shreveport, LA 71162 | Oil & Gas Operator | Apr 2024 |
| 115 | Summit Gas Resources Inc | Sheridan, WY 82801 | Gas Operator | Dec 2023 |
| 116 | Summit Operating LLC | Boulder, CO 80301 | Oil & Gas Operator | Feb 2024 |
| 117 | Summit Resources, Inc. | Houston, TX 77077 | Oil & Gas Operator | Sep 2016 |
| 118 | Suncor Energy Natural Gas America Inc | Greenwood VIllage, CO 80111 | Gas Operator | Feb 2010 |
| 119 | Sundance Energy Inc | Denver, CO 80202 | Oil & Gas Operator | Jul 2014 |
| 120 | Sundance Oil Exploration Co | | Oil Operator | Mar 1986 |
| 121 | Sunshine Valley Petroleum | Casper, WY 82605 | Oil & Gas Operator | Feb 2024 |
| 122 | Supron Energy Corp | | Oil & Gas Operator | Oct 1995 |
| 123 | Surtek Inc | | Oil & Gas Operator | May 1993 |
| 124 | Survivor Oil Inc | Tulsa, OK 74133 | Oil & Gas Operator | Sep 2007 |
| 125 | Swenco-Western Inc | Houston, TX 77060 | Oil & Gas Operator | Jan 1997 |
| 126 | Swepi LP | Houston, TX 77079 | Oil & Gas Operator | Jul 2020 |
| 127 | Swift Energy Company | Houston, TX 77060 | Oil & Gas Operator | Mar 2021 |
| 128 | Synergy Offshore LLC | Houston, TX 77024 | Oil & Gas Operator | Feb 2022 |
| 129 | Synergy Operating LLC | Farmington, NM 87499 | Oil & Gas Operator | Feb 2024 |