DOI: 10.5176/2251-3361_GEOS12.56
Authors: Thomas Millan, Teddy Parra, Eric Lécolier, Bernard Guy, Jacques Moutte
Abstract:
Geological storage of CO2could be a viable way of limiting the effect of anthropogenic carbon dioxide emissions on the global warming. However, the containment of the gas has to be ensured and the understanding of how CO2could leak out of the sequestration formation is of great importance. The loss of the integrity of one or several wells located on the storage site represents the greatest risk of CO2leakage. For example, cement carbonation is one of the mechanism which can impair sealing capacity of a well. The knowledge of the long-term evolution of a hardened Portland cement exposed to CO2-rich fluids is therefore a key issue to ensure confidence in CO2geological storage. Reactive transport modeling appears as the most reliable way to forecast the cement annular behavior at very long term. However, reactive transport codes require reliable input thermodynamic data. A thermodynamic dataset based only on calorimetric data does not guaranty accurate results. Furthermore, a combination of reversal brackets and calorimetry is a way of getting an internally consistent thermodynamic dataset. The existing internally consistent thermodynamic databases include important phases concerning cements as portlandite, calcium carbonates or some calcium silicate hydrates (CSH) that may occur in a hydrated cement paste. The purpose of this study is to obtain new experimental results relative to the stability conditions of gyrolite (Ca4Si6O17H2) under well constrained pressure-temperature conditions. These bracketing experiments provide constrains to optimize and estimate thermodynamic data of the studied mineral.
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