| 101 | Sealexco-Crescent Drilling | | Oil & Gas Operator | May 1986 |
| 102 | Seawide Limited | | Oil & Gas Operator | Jul 1983 |
| 103 | Secan Oil Co Inc | | Oil & Gas Operator | May 1987 |
| 104 | Secan Oil Co., Inc.-Pennington | | Oil & Gas Operator | May 1987 |
| 105 | Secondary Recovery, Inc. | | Oil & Gas Operator | Dec 1991 |
| 106 | Sedona Oil & Gas Corporation | Dallas, TX 75231 | Oil & Gas Operator | Feb 2026 |
| 107 | Segars Energy | | Gas Operator | Mar 2001 |
| 108 | Segars Operating | | Gas Operator | Apr 2014 |
| 109 | Sei Operating, LLC | Mandeville, LA 70471 | Oil & Gas Operator | Feb 2026 |
| 110 | Semo, Inc. | | Oil & Gas Operator | Feb 2002 |
| 111 | Sendero Energy Inc. | Dallas, TX 75205 | Oil & Gas Operator | Feb 2026 |
| 112 | Seneca Resources Corporation | Houston, TX 77002 | Oil & Gas Operator | Dec 2017 |
| 113 | Seneca-Cashco | | Oil & Gas Operator | Sep 1986 |
| 114 | Senior Drilling & Expl Co Inc. | | Oil & Gas Operator | Apr 1993 |
| 115 | Senior G&A Operating Co Inc | | Oil & Gas Operator | Nov 1991 |
| 116 | Sensor Oil & Gas, Inc. | Duncan, OK 73534 | Oil & Gas Operator | May 2013 |
| 117 | Sepulvado Oilfield Service Inc | | Oil & Gas Operator | Jul 2010 |
| 118 | Serio Energy Corporation | | Oil & Gas Operator | Jul 2000 |
| 119 | Serio Exploration Company | | Oil Operator | Jan 1992 |
| 120 | Serio Oil Corp. | | Oil & Gas Operator | Sep 1991 |
| 121 | Serio Operating Co. | | Oil & Gas Operator | Mar 2007 |
| 122 | Ses Production | | Oil & Gas Operator | Oct 2023 |
| 123 | Setex Oil And Gas Company | Houston, TX 77002 | Oil & Gas Operator | Feb 2012 |
| 124 | Settco Oil & Gas | | Oil & Gas Operator | May 1994 |
| 125 | Sevarg Company, Inc. | | Oil & Gas Operator | Feb 2016 |
| 126 | Sewell Development Co Inc | | Oil & Gas Operator | Apr 1993 |
| 127 | SG Interests, Inc. | Houston, TX 77010 | Oil & Gas Operator | Jun 2007 |
| 128 | Shadrack Production Company | | Gas Operator | Dec 1982 |
| 129 | Shale Energy International, LLC | | Oil & Gas Operator | Nov 2024 |
| 130 | Shana Petroleum Company | Dallas, TX 75206 | Oil & Gas Operator | Aug 2002 |
| 131 | Shannon Williams | | Oil Operator | Jan 1993 |
| 132 | Shaw-Laird, LLC | | Oil & Gas Operator | Jan 2017 |
| 133 | Shelby H. Loe, SR. Oil Co. | | Oil Operator | Jul 1989 |
| 134 | Shelby Operating Company | Dallas, TX 75205 | Oil & Gas Operator | Feb 2026 |
| 135 | Shelf Energy, LLC | | Oil & Gas Operator | Dec 2024 |
| 136 | Shell Offshore Inc. | New Orleans, LA 70161 | Oil & Gas Operator | Jan 2008 |
| 137 | Shell Oil Co. | Houston, TX 77001 | Oil & Gas Operator | Jun 1985 |
| 138 | Shell Western E&P Inc. | Houston, TX 77001 | Oil & Gas Operator | May 2011 |
| 139 | Shenandoah Oil Corporation | | Oil & Gas Operator | Jun 1979 |
| 140 | Sheridan Energy,Inc. | Houston, TX 77002 | Oil & Gas Operator | Feb 2000 |
| 141 | Shield Energy Resources, LLC | | Oil Operator | Dec 2024 |
| 142 | Shiloh Creek Resources, Inc. | | Gas Operator | Nov 2024 |
| 143 | Sho-Van Gas Producing Co. | | Gas Operator | Aug 1990 |
| 144 | Shocker Energy, Inc. | | Oil & Gas Operator | Oct 1992 |
| 145 | Shoco Production, L.P. | Kilgore, TX 75663 | Oil & Gas Operator | May 2020 |
| 146 | Shongaloo Midstream, LLC | | Oil Operator | Mar 2019 |
| 147 | Shore Oil Company | | Oil & Gas Operator | May 1998 |
| 148 | Shoreline Exploration Of Texas | | Oil & Gas Operator | Oct 2000 |
| 149 | Shoreline Exploration, Inc. | | Oil & Gas Operator | Jul 1990 |
| 150 | Shoreline GP LLC | | Oil & Gas Operator | Jun 2012 |
| 151 | Shoreline Offshore LLC | | Oil & Gas Operator | Jun 2017 |
| 152 | Shoreline Petroleum Corp. | Channelview, TX 77530 | Oil & Gas Operator | Sep 2003 |
| 153 | Shoreline Pipeline Corporation | | Oil Operator | Dec 2020 |
| 154 | Shoreline Southeast LLC | | Oil & Gas Operator | Jun 2017 |
| 155 | SHS Operating Company | Shreveport, LA 71149 | Oil & Gas Operator | Jan 2025 |
| 156 | Shufflin Energy | | Oil & Gas Operator | Sep 2011 |
| 157 | Shuler Drilling Co., Inc. | El Dorado, AR 71730 | Oil & Gas Operator | Jan 2025 |
| 158 | Shuler DRLG Co &Roy Guffey Oil | | Oil & Gas Operator | Sep 1992 |
| 159 | Shuteston Oil & Gas | | Oil & Gas Operator | Sep 1997 |
| 160 | Sierra Industries, Inc. | | Oil & Gas Operator | Apr 1989 |
| 161 | Sierra Oil & Gas Corp. | | Gas Operator | Dec 1979 |
| 162 | Sierra Production Company | | Oil & Gas Operator | May 1986 |
| 163 | Sigma Energy, LLC | | Oil Operator | Jan 2025 |
| 164 | Signal Oil And Gas Company | Colleyville, TX 76034 | Oil & Gas Operator | Feb 2026 |
| 165 | Signal Operating L.L.C. | | Oil Operator | Jan 2025 |
| 166 | Signal Petroleum | | Oil & Gas Operator | Jul 1980 |
| 167 | Signal, LLC Of Mississippi | | Oil & Gas Operator | Dec 2024 |
| 168 | Silver Creek Oil & Gas, LLC | Flower Mound, TX 75022 | Oil & Gas Operator | Feb 2026 |
| 169 | Silver Hill Energy Operating, LLC | Dallas, TX 75201 | Oil & Gas Operator | Feb 2026 |
| 170 | Silver Oak Energy, LLC | Fort Worth, TX 76102 | Oil & Gas Operator | Apr 2016 |
| 171 | Silver Oak Operating, Inc. | Longview, TX 75601 | Oil & Gas Operator | Dec 2009 |
| 172 | Silver Oak Operating, LLC | Longview, TX 75604 | Oil & Gas Operator | Feb 2026 |
| 173 | Silver Pines Energy Corp. | Houston, TX 77005 | Oil & Gas Operator | Nov 2025 |
| 174 | Simar Petroleum, LLC | | Oil Operator | Dec 2024 |
| 175 | Simco Oil Company | | Oil Operator | Jul 1990 |
| 176 | Simmons Oil Corp | | Oil Operator | Jan 1989 |
| 177 | Simpson Well Service, Inc. | | Oil Operator | Dec 1996 |
| 178 | Singer-Fleischaker Oil Co Inc | | Oil & Gas Operator | Jul 1987 |
| 179 | Singer-Fleischaker Oil Op Co | Oklahoma City, OK 73102 | Oil & Gas Operator | Apr 2002 |
| 180 | Singer-Fleischaker,Dillon | | Oil & Gas Operator | Aug 1979 |
| 181 | Single Barrel Oil And Gas LLC | Granbury, TX 76048 | Oil & Gas Operator | Feb 2026 |
| 182 | Sitwell, Inc. | | Oil Operator | May 2022 |
| 183 | Skelly Oil Co | | Oil & Gas Operator | Mar 2005 |
| 184 | Skinner Energy Management, Inc. | Shreveport, LA 71135 | Oil & Gas Operator | Jan 2011 |
| 185 | Sklar & Phillips - Harry Hurt | | Oil & Gas Operator | Jul 1986 |
| 186 | Sklar & Phillips Oil Co. | Shreveport, LA 71101 | Oil & Gas Operator | Dec 2000 |
| 187 | Sklar & Phillips Oil Co.-Entex | | Oil & Gas Operator | Aug 1978 |
| 188 | Sklar &Phillips-Great Southern | | Oil & Gas Operator | Aug 1980 |
| 189 | Sklar Exploration Company LLC | Shreveport, LA 71101 | Oil & Gas Operator | Feb 2026 |
| 190 | Skrivanos Engineering, Inc. | Shreveport, LA 71164 | Oil & Gas Operator | Dec 2011 |
| 191 | Skyhawk Energy, LLC | | Oil Operator | Dec 2024 |
| 192 | Skyline Oil Company | Salt Lake City, UT 84111 | Oil & Gas Operator | Jan 1987 |
| 193 | SKZ Inc. | | Oil Operator | Mar 1988 |
| 194 | Slam Resources, Inc. | | Oil & Gas Operator | Apr 1994 |
| 195 | Slapco - Emerald Exploration | | Gas Operator | Sep 1979 |
| 196 | Sleeth And Brooks Oil Co. | | Oil Operator | Jul 1989 |
| 197 | SM Energy Company | Midland, TX 79707 | Oil & Gas Operator | Feb 2026 |
| 198 | Smackover Drilling Co. Inc. | Shreveport, LA 71105 | Oil & Gas Operator | Jan 2025 |
| 199 | Smal Energy Corp | Tyler, TX 75710 | Oil & Gas Operator | Oct 1995 |
| 200 | SMC Oil & Gas, Inc. | Midland, TX 79710 | Oil & Gas Operator | Feb 2026 |