The Greater Green River Basin (GGRB) of Wyoming (Fig 1) has produced abundant oil and gas out of multiple reservoirs for over 60 years, and large quantities of gas remain untapped in tight gas sandstone reservoirs Recent gas resource estimates for low permeability Cretaceous and Tertiary reservoirs in the GGRB range from 1,968 TCF in place (the Scotia Group) to 5,064 TCF in place (U S Geological Survey) (DOE Topical Report by the Scotia Group, 1993) Current activity, including the Greater Green River Basin Production Improvement Project, is focusing on ways to convert this vast resource into economically recoverable gas