Mineral Grain Spatial Patterns and Reaction Rate Up-scaling

Reactive transport models that describe mineral reactions in porous media rely on laboratory measurements of rate parameters that may fail to represent reactions defined at larger averaging scales. In recently completed work, we used pore-scale network models to investigate the effects of heterogeneities in pore structure and mineral distribution on geochemical reaction rates in porous media. Our findings revealed significant scaling effects from variations in reactive mineral distribution, especially for the highly acidic conditions encountered in geological sequestration of carbon dioxide. In this paper we present preliminary findings from electron scanning BSE maps, to analyze spatial patterns of minerals in sedimentary rocks. Samples include sandstones from the Viking formation in the Alberta basin in western Canada. Image analysis was used to quantify pore space and examine reactive minerals in relation to pore locations. Typically, reactive minerals occur as distinct grains and inclusions, and their percent abundance is larger than the extent of their contact