472020 Numerical Modeling of CO2 Sequestration in Deep, Saline, Dolomitic-Limestone Aquifers
Results from the study suggest that solubility trapping accounts for the highest amount of CO2 sequestered as compared to mineral and residual trapping. Due to formation of carbonic acid, the pH of the brine dropped to below 5. This drop in pH led to dissolution of minerals like calcite and dolomite. Also, there was precipitation of minerals like gypsum. Changes in porosity and permeability due to dissolution and precipitation of minerals have been estimated. Although the study was conducted primarily for calcite, dolomite, and gypsum, it may be applicable to other formations as well. The study gives an overall estimate of the amount of CO2 sequestered under different conditions (salinity, pressure, temperature, and mineralogy). It also predicts the changes in chemistry and permeability of the system under different conditions. The study thereby helps to choose the feasibility of sites for CO2 sequestration more efficiently.
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