DISSOLUTION OF MINERAL CARBONATES WITH INCREASING CO2 PRESSURE AND THE IMPLICATIONS FOR CARBON SEQUESTRATION LEAK DETECTION

Carbonate minerals are wide spread components of geological formations associated with the storage of carbon dioxide. The stability of these minerals may be affected due to leaking CO₂ and the resulting precipitation/dissolution reactions could lead to a certain geochemical transformations. Although geochemical modeling predicts the pH-dependent stability of these minerals, in situ experiments are needed to support the model predictions. In this study, we applied underwater laser-induced breakdown spectroscopy for measuring in situ dissolution of various mineral carbonates (MgCO₃, CaCO₃, SrCO₃, and MnCO₃) in the presence of increasing CO₂ pressure ranging from 25-350 bar. A pulsed Nd:YAG laser at 1064 nm was used to produce gaseous plasma in the fluid surrounding pressed pellet of the carbonate powders. The ensuing plasma emission was spectrally analyzed, and the intensity of the Mg, Ca, Sr, and Mn emission lines were used to monitor their respective divalent cations (Mg²⁺, Ca²⁺ , Sr²⁺, and Mn²⁺) released to the aqueous solution. The results suggest that carbonate dissolution may provide a useful indirect detection system indicative of CO₂ leakage from some storage sites.