Interaction between a fractured marl caprock and CO 2 -rich sulfate solution under supercritical CO 2 conditions

Abstract : Geological CO2 sequestration at pilot-plant scale will be developed at Hontomín (Spain). CO2 will be injected into a limestone reservoir that contains a NaCl- and sulfate-rich groundwater in equilibrium with calcite and gypsum. The caprock site is composed of marl. The present study seeks to evaluate the interaction between the Hontomín marl and CO2-rich sulfate solutions under supercritical CO2 conditions (PTotal = 150 bar, pCO2 = 61 bar and T = 60 °C). Flow-through percolation experiments were performed using artificially fractured cores to elucidate (i) the role of the composition of the injected solutions (S-free and S-rich solutions) and (ii) the effect of the flow rate (0.2, 1 and 60 mL h−1) on fracture permeability. Major dissolution of calcite (S-free and S-rich solutions) and precipitation of gypsum (S-rich solution) together with minor dissolution of the silicate minerals contributed to the formation of an altered skeleton-like zone (mainly made up of unreacted clays) along the fracture walls. Dissolution patterns changed from face dissolution to wormhole formation and uniform dissolution with increasing Peclet numbers. In S-free experiments, fracture permeability did not significantly change regardless of the flow rate despite the fact that a large amount of calcite dissolved. In S-rich solution experiments, fracture permeability decreased under slow flow rates (0.2 and 1 mL h−1) because of gypsum precipitation that sealed the fracture. At the highest flow rate (60 mL h−1), fracture permeability increased because calcite dissolution predominated over gypsum precipitation.
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Contributeur : Linda Luquot <>
Soumis le : jeudi 17 octobre 2019 - 18:23:52
Dernière modification le : samedi 19 octobre 2019 - 01:23:30

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Gabriela Dávila, Linda Luquot, Josep Soler, Jordi Cama. Interaction between a fractured marl caprock and CO 2 -rich sulfate solution under supercritical CO 2 conditions. International Journal of Greenhouse Gas Control, Elsevier, 2016, 48, pp.105-119. ⟨10.1016/j.ijggc.2015.11.005⟩. ⟨hal-02319298⟩



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