Abstract

Coal and coal gas resources were estimated for the Upper Cretaceous Mesaverde Group and lower Tertiary Fort Union Formation in the Greater Green River Basin. Resources for the Greater Green River Basin are 1277 billion short tons of coal and 314 tcf of coal gas assuming no depth restrictions, whereas 688 billion short tons of coal and 84 tcf of gas occur at depths of 7500 ft or less. The Mesaverde Group, consisting of the Rock Springs and Williams Fork (and equivalent) Formations, and the Fort Union Formation contain nearly equal amounts of coal (628 billion and 649 billion short tons, respectively). However, nearly 85% of the coal gas resources are found in the Mesaverde Group, reflecting greater maximum burial depths and higher coal rank. Significant coal gas resources in the Mesaverde Group are located in the Sand Wash Basin and off the northeast flank of the Rock Springs uplift where gas resources can exceed 70 bcf/mi².