Shale Gas Reservoirs of Utah

Steven Schamel, GeoX Consulting Inc, 1265 Yale Avenue, Salt Lake City, UT 84105, phone: 801 583-1146, fax: 801 583 1356, [email protected]

Organic-rich shales are found throughout Utah, several of which are possible candidates for future shale gas production. The criteria for assessing the natural gas potential of these shale units included (1) probable gas content as estimated from kerogen/bitumen content, level of organic maturity and petrophysical properties; (2) thickness and lateral extent of the shale under conditions for gas generation/retention; and (3) suitability for successful fracture stimulation. The open lacustrine black shale facies of the Green River Formation (Eocene) possesses good potential for large gas yields where in the gas generative window beneath the Uinta basin, but resource development may be difficult and expensive. Shallow microbial gas from this black shale is known, but commercialization in significant quantities is unlikely. The Prairie Canyon (Mancos B) and Juana Lopez Members of the Mancos Shale (Upper Cretaceous), neither a conventional black shale, are excellent candidates for developing large volumes of add-on gas in the southern Uinta basin. The lithologically similar and slightly older Tropic Shale (Turonian) may locally produce significant quantities of add-on gas in association with future deep CBM development in southern Utah. The Mowry Shale (Lower Cretaceous) has excellent potential as a shale gas reservoir, but future exploitation will be restricted to just limited areas north of the Uinta Mountains. The Manning Canyon Shale (Mississippian-Pennsylvanian) and Delle Phosphatic Shale Member (Mississippian) are organic-rich and widespread through western Utah, but due to a variety of inherent problems these deposits are likely to be exploited for gas only in very restricted areas and quantities.