VARIABILITY IN THE GEOCHEMICAL MODELING OF CARBON SEQUESTRATION OF A SANDSTONE AQUIFER

A geochemical model was utilized to estimate the amount of CO2 sequestered in dissolved and mineral phases in a sandstone aquifer. This fictitious aquifer was built to resemble as much as possible the St. Francois aquifer in SW Missouri, which is under investigation at the present time as a pilot study site for carbon sequestration. The input parameters to the geochemical model were selected to represent the injection conditions and presumed aquifer characteristics of the site under consideration. Analysis of variance was applied to the model input/output to identify which parameters (e.g., confining pressure, temperature, clay content, and iron oxide content) contribute the most to output variability and which variations are rendered irrelevant for sequestration purposes. Besides validating the performance of the model, the results are useful in identifying the parameters that may require additional research to strengthen the accuracy of the results once the local field parameters (lithology, water chemistry, temperature) become available. This material is based upon work sponsored by the Department of Energy National Energy Technology Laboratory under Award No. DE-NT0006642 to City Utilities of Springfield, MO.