CO2 partial pressure in clayrocks: a general model

Eric C. Gaucher (1) , Arnault Lassin (1) , Catherine Lerouge (1) , Christine Fléhoc (1) , Nicolas C.M. Marty (1) , Benoît Henry (1) , Christophe Tournassat (1) , Scott Altmann (2) , Agnès Vinsot (3) , Stéphane Buschaert (2) , J.M. Matray (4) , O.X. Leupin (5) , M. de Craen (6)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 ANDRA - Agence Nationale pour la Gestion des Déchets Radioactifs
3 ANDRA
4 IRSN/DEI/SARG/LETS - Laboratoire d'étude des transferts dans les sols et le sous-sol
5 NAGRA - Nationale Genossenschaft für die Lagerung radioaktiver Abfälle
6 SCK-CEN - Centre d'Etude de l'Energie Nucléaire

An initial geochemical characterization of clayrocks is needed in order to evaluate their feasibility for use as caprocks or host formations for greenhouse gas storage or nuclear waste disposal facilities, respectively. In this context, a method was developed for the measurement of CO2 partial pressure in clayrock pore water. The PCO2 was systematically acquired using core samples obtained from underground laboratories located at 4 locations in Europe. The isotope ratios (C, O) of the gas and of the carbonate minerals were also obtained. The stable isotope ratios limit the possible origins of the CO2 to a thermodynamic equilibrium between aqueous solution species and the diagenetic carbonate minerals (calcite, dolomite), and a Mg-aluminosilicate.

Keywords: PCO2; clayrocks; argilites; model

Domains: Geochemistry; Global Changes

Eric C. Gaucher, Arnault Lassin, Catherine Lerouge, Christine Fléhoc, Nicolas C.M. Marty, et al.. CO2 partial pressure in clayrocks: a general model. Water-Rock Interaction WRI-13, Aug 2010, Guanajuato, Mexico. pp.855-858. ⟨hal-00664967⟩