Abstract
The ultimate capacity of saline formations to sequester carbon dioxide
by solubility and mineral trapping must be determined by simulating
sequestration with geochemical models. These models, however, are
only as reliable as the data and reaction scheme on which they are
based. Several models have been used to make estimates of carbon
dioxide solubility and mineral formation as a function of pressure
and fluid composition. Intercomparison of modeling results indicates
that failure to adjust all equilibrium constants to account for elevated
carbon dioxide pressures results in significant errors in both solubility
and mineral formation estimates. Absence of experimental data at
high carbon dioxide pressures and high salinities make verification
of model results difficult. Results indicate standalone solubility
models that do not take mineral reactions into account will underestimate
the total capacity of aquifers to sequester carbon dioxide in the
long term through enhanced solubility and mineral trapping mechanisms.
Overall, it is difficult to confidently predict the ultimate sequestration
capacity of deep saline aquifers using geochemical models. (c) 2005
Elsevier B.V. All rights reserved.
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