HYDROGEOCHEMICAL EVALUATION OF THE GREEN RIVER AND UINTA FORMATION OF THE PICEANCE CREEK BASIN, NORTHWESTERN COLORADO

The Piceance Creek Basin in northwestern Colorado contains extensive oil shale deposits which could potentially yield 1.5 trillion barrels of shale oil. However, much of the oil shale lies at depths too great for traditional mining practices. Various innovative approaches for in situ conversion of kerogen to oil have been proposed. Critical to their success is a firm understanding of the existing hydrogeochemistry as mineralogical changes or rock-fluid reactions may affect porosity, permeability and the composition of groundwaters when heated. Previous studies largely focus on bedrock lithologies and origins of the shale and related units. The objective of this study is to evaluate the aqueous chemistry of the Basin using existing data in terms of mineralogical controls (saturation indices) and residence times (sample depths and position along presumed flow paths). The results of the study will be useful in predicting changes resulting from these alternative methods of oil shale development.