Carbon capture and sequestration (CCS) has been proposed a way to mitigate global climate change due to fossil fuel combustion. Therefore, protecting subsurface resources (i.e., groundwater) is an important component of CCS risk assessment. Although reactive transport modeling and simulations can anticipate expected geochemical transformations due to CO2 leaks within a given aquifer, field experiments are necessary to critique model predictions and to document in situ reaction rates. Geological formations at and around a storage site may include a wide range of reactive silicate, oxide, oxyhydroxide, carbonate, and sulfide minerals. The composition of these minerals may be affected when aqueous chemical equilibria are modified by the leaking CO2. In this study, we propose the use of laser induced breakdown spectroscopy (LIBS) to monitor the dissolution of synthesized carbonate minerals in the presence of CO2. LIBS has a real-time monitoring capability and can be reliably used for elemental analysis of solid, liquid, and gas samples. We have successfully used the technique to conduct laboratory-scale experiments to measure calcium and other cations in aqueous samples. Stability fields for a wide range of carbonate minerals over a pH range of 5-8 were determined by geochemical modeling. Experiments detected increases in dissolved calcium due to incremental CO2 gas in the presence of synthetic calcium carbonate. The ultimate aim of this research is to develop a field-deployable LIBS instrument for in situ monitoring of CO2 leakage into groundwater aquifers. Additional field sensor approaches based on the dissolution of novel mineral carbonate microspheres will also be presented.

Use of LIBS to detect CO2 leaks from geological storage based on mineral carbonate interactions in groundwater

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.