Currently, DOE is conducting the pilot CO(sub 2) injection tests to evaluate the concept of geologic sequestration. One strategy that potentially enhances CO(sub 2) solubility and reduces the risk of CO(sub 2) leak back to the surface is dissolution of indigenous minerals in the geological formation and precipitation of secondary carbonate phases, which increases the brine pH and immobilizes CO(sub 2). Clearly, the rates at which these dissolution and precipitation reactions occur directly determine the efficiency of this strategy. However, one of the fundamental problems in modern geochemistry is the persistent two to five orders of magnitude discrepancy between laboratory-measured and field derived feldspar dissolution rates. To date, there is no real guidance as to how to predict silicate reaction rates for use in quantitative models. Current models for assessment of geological carbon sequestration have generally opted to use laboratory rates, in spite of the dearth of such data for compositionally complex systems, and the persistent disconnect between lab and field applications. Therefore, a firm scientific basis for predicting silicate reaction kinetics in CO(sub 2) injected geological formations is urgently needed to assure the reliability of the geochemical models used for the assessments of carbon sequestration strategies.
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