| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Mark Resources Corp | Pittsburgh, PA 15276 | Oil & Gas Operator | Dec 1993 |
| 2 | Mat Oil & Gas Exploration Inc | Indiana, PA 15701-8931 | Gas Operator | Dec 1993 |
| 3 | McCluskey J Sterling | New York, NY 10128-1008 | Gas Operator | Dec 1989 |
| 4 | Meadville Forging Co LP | Meadville, PA 16335-0459 | Gas Operator | Dec 1997 |
| 5 | Medina Res Dev Co LLC | Cambridge Springs, PA 16403-3447 | Oil & Gas Operator | Dec 2025 |
| 6 | Meridian Exploration Corp. | Pittsburgh, PA 15222 | Oil & Gas Operator | Dec 2021 |
| 7 | Meridian Oil & Gas Enterprises Inc | Blairsville, PA 15717-0337 | Oil & Gas Operator | Dec 2003 |
| 8 | Mitch Well Energy Inc | Waterford, PA 16441-8143 | Oil & Gas Operator | Dec 2012 |
| 9 | Mitchell Energy Corp | Houston, TX 77002 | Oil & Gas Operator | Aug 2013 |