HR: 1340h
AN: GC13A-1217    [Abstracts]
TI: Numerical Studies of CO2 Leakage from Geologic Storage Reservoirs
AU: * Pruess, K
EM: K_pruess@lbl.gov
AF: Lawrence Berkeley National Laboratory, MS 90-1116, Berkeley, CA 94720 United States
AB: Storage of CO2 in geologic formations offers attractive possibilities for near-term reductions of atmospheric emissions of this greenhouse gas. In order to make a significant impact, large amounts of CO2 would need to be stored. CO2 plumes would extend over large areas of order 100 sq. km or more, making it likely that geologic features such as fracture zones and faults would be encountered, that would offer pathways along which stored CO2 could escape to the land surface. Migration of CO2 could also occur along man-made pathways, such as abandoned wells. Escape of CO2 from the primary storage reservoir raises a number of concerns, such as keeping CO2 away from the atmosphere, and avoiding acidification of groundwater and asphyxiation hazards at the land surface. Developing an understanding of how CO2 may migrate in natural hydrogeological environments is necessary in order that potential hazards may be identified and avoided, and methods for monitoring of CO2 discharges may be assessed. The manner in which CO2 would escape and migrate away from a primary storage reservoir depends on thermodynamic conditions in the subsurface (pressure, temperature, salinity of ambient fluids, mineralogy, etc.), as well as on the hydrogeologic conditions encountered. We have used numerical simulation to investigate the manner in which CO2 may migrate along localized preferential flow paths as a free phase or dissolved in ambient groundwaters or brines. Our studies demonstrate a tendency for CO2 leakage to occur in a non-monotonic manner, either due to couplings between fluid flow and heat transfer, or due to cyclic pressure variations associated with exsolution-dissolution effects. In the volcanology literature it has been suggested that compressed CO2 may be capable of generating a self-enhancing runaway discharge that would culminate in a pneumatic eruption. Our studies have identified self-limiting effects during CO2 discharges which suggest that such behavior is unlikely and may well be impossible. This work was supported by the Zero Emission Research and Technology project (ZERT) under contract no. DE-AC03-76SF00098 with the U.S. Department of Energy.
DE: 1831 Groundwater quality
SC: Global Climate Change [GC]
MN: Fall Meeting 2005