HR: 1340h
AN: U43C-1378    [Abstracts]
TI: Formation Buffering Potential Pertaining to Geological Storage of Carbon Dioxide
AU: * Ellis, B R
EM: brellis@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08540, United States
AU: Peters, C A
EM: cap@princeton.edu
AF: Princeton University, Department of Civil and Environmental Engineering, Princeton, NJ 08540, United States
AU: Buschkuehle, M
EM: Maja.Buschkuehle@gov.ab.ca
AF: Alberta Geological Survey, 4999-98 Avenue, Edmenton, AB T6B 2X3, Canada
AB: One promising strategy for decreasing CO₂ emissions to the atmosphere is carbon capture and storage in deep saline formations. Modeling efforts and the experimental measurements that support these efforts are critical to determining the fate of injected CO₂. The focus of this work is CO₂-water-rock interactions as they pertain to formation buffering potential. PHREEQC was used to model pH evolution in siliciclastic and carbonate rocks after simulated injection of CO₂. The initial mineral and formation water compositions were determined from analysis of core samples and brines from several formations in the Alberta sedimentary basin in western Canada. Simulation parameters correspond to injection conditions of 50°C, CO₂ pressure of 100 bar and high ionic strength. Results indicate that the carbonate formations have a higher buffering potential relative to siliciclastic formations. Considerable variability of acid-catalyzed reactions among formations with similar mineralogical compositions was also observed. To assess the effect of grain coating by clay minerals, a comparative simulation was performed with kaolinite as the dominant mineral in contact with the pore fluids. Results from this simulation showed a pronounced retardation in pH buffering reaction kinetics. This emphasizes the importance for differentiating between mineral abundance and accessibility in model calculations when clay coatings may obscure contact between pore fluids and potentially reactive minerals.
DE: 1009 Geochemical modeling (3610, 8410)
SC: Union [U]
MN: 2007 Fall Meeting