A robust model for pore-water chemistry of clayrock

摘要: The chemistry of pore water is an important property clayrocks being considered as host rocks for long-term storage radioactive waste. It may be difficult, if not impossible, to obtain samples chemical analysis from such because their low hydraulic conductivity. This paper presents approach calculating the pore-water compositions laboratory-measured properties core samples, including leachable Cl and SO4 concentrations analysed exchangeable cations, mineral cation exchange equilibria based on formation mineralogy. New sampling procedures are presented that reduce or quantify side reactions sample oxidation (e.g. pyrite) soluble dissolution (celestite, SrSO4) affect measured distributions. model considers phase only with minerals observed in principal clay phases. has been used calculate composition mobile Callovo-Oxfordian clayrock validated against measurements made underground research laboratory formation. reproduces measured, situ without any estimated parameters. All required parameters can obtained analysis. We highlight need consider those phases which shown equilibrium contacting water. consequence this some conceptual models available literature appear appropriate modelling clayrocks, particularly considering high temperature and/or pressure detrital buffers robustness our respect uncertainties log K values also demonstrated. Large have relatively small effects modelled compositions.