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Accessing effects and signals of leakage from a CO2 reservoir to a shallow freshwater aquifer by reactive transport modelling

Szabó, Zsuzsanna, Gál, Nóra Edit, Kun, Éva, Szőcs, Teodóra, Falus, György
Environmental earth sciences 2018 v.77 no.12 pp. 460
aquifers, carbon dioxide, climate change, cost effectiveness, drinking water, electrical conductivity, freshwater, models, monitoring, porosity, water supply, Hungary
CO₂ geological storage is a transitional technology for the mitigation of climate change. In the vicinity of potential CO₂ reservoirs in Hungary, protected freshwater aquifers used for drinking water supplies exist. Effects of disaster events of CO₂ escape and brine displacement to one of these aquifers have been studied by kinetic 1D reactive transport modelling in PHREEQC. Besides verifying that ion concentrations in the freshwater may increase up to drinking water limit values in both scenarios (CO₂ or brine leakage), total porosity of the rock is estimated. Pore volume is expected to increase at the entry point of CO₂ and to decrease at further distances, whereas it shows minor increase along the flow path for the effect of brine inflow. Additionally, electrical conductivity of water is estimated and suggested to be the best parameter to measure for cost-effective monitoring of both worst-case leakage scenarios.