Geochemistry of Geologic Sequestration of Carbon Dioxide

Abstract

Geologic sequestration of carbon dioxide (CO 2 ) is considered one plausible option to reduce green - house gases (GHGs) emissions to mitigate global warming and related climate changes. Geochemical s udies are essential for providing improved understanding of CO 2 - brine - mineral interactions, which strongly affect storage injectivity and security. Reservoir capacity and integrity are strongly dependent on the four main CO 2 - trapping mechanisms: 'structural' , 'residual' , 'solution' and 'mineral' . The bulk of CO 2 will be stored initially as a supercritical fl uid, with some rapidly dissolving in formation water, but mineral and additional solution - trapping will be slower, yet more permanent. Results from natural analogues indicate that dissolution in brine is the major sink for CO 2 . Geochemical results from Frio tests (Texas) proved powerful in: (i) tracking the successful injection of CO 2 ; (ii) detecting CO 2 in the overlying 'B' sandstone; (iii) showing mobilization of metals and organics, and major changes in chemical and isotopic compositions of brine. Modelling and Fe isotopes indicate dissolution of calcite and Fe - oxyhydroxides, and well - pipe corrosion. ©2011 Blackwell Publishing Ltd. © 2011 Blackwell Publishing Ltd. All rights reserved.