S Wang¹, P.R. Jaffe², M.A. Celia², S.C. Myneni², C.A. Peters², J.H. Prevost²

(1) Princeton University, Princeton, NJ
(2) Princeton University

ABSTRACT: Effect of CO2 Releases from Deep Reservoirs on the Quality of Fresh-Water Aquifers

Injection of supercritical CO2 into deep saline aquifers is a promising technique for sequestration of large amounts of CO2. Because complete characterization of these geological formations is not possible, it is likely that some fraction of the injected CO2 will leak into overlying aquifers. If the leaking CO2 were to reach shallow groundwater aquifers, it would lead to geochemical alterations that could have detrimental effects on the water quality. Identification and assessment of these effects are necessary to adequately analyze risks associated with geologic sequestration.

In order to assess if there is a potential of solubilizing trace metals, metalloids, and/or selected radioisotopes by CO2 releases, a series of simulations were conducted. We have simulated, for a distribution of CO2 release scenarios and different aquifer geochemical properties, the effect of pH changes induced by CO2 using a combination of geochemical and transport models. Results show that CO2 saturation in freshwater aquifers can clearly solubilize several trace metals to undesirable levels at the local scale. Transport models demonstrate the importance of assessing the areal extent of this CO2 release, as well as the need to gain an understanding of the key kinetic processes related to CO2 solubilization and trace metal dissolution.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado