摘要：

Effect of the aqueous chemistry on the mechanical strength of chalk has extensively been studied during the last decade. At high temperatures (~130°C), chalk exposed to seawater is significantly weaker compared to chalk exposed to distilled water when considering the hydrostatic yield strength and the following creep phase. The explanation of these experimental results must be of a chemical nature, as the density and viscosity of the aqueous phase vary little among these different brines. We present the results from simplified aqueous chemistry using MgCl2 brines, and compare these results with seawater. Previous studies show that different ions, e.g. Ca2+, Mg2+, SO42-{{m SO}{_{4}}^{2-}} in the injected brine, as well as the chalk mineralogy have an impact on the stability of the rock. We performed mechanical tests on chalk cores from Liège and Stevns Klint; it was found

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