Conferenciant: Eric Oelkers, Laboratoire des Mécanismes et Trensfers en Géologie (LMTG), Tolosa, França.

Dimecres, 5 d'abril, sala d'Actes de l'Institut Jaume Alemera, 12 h.

Much current effort on surrounding CO2 storage in the subsurface is aimed at its injection in sedimentary rock, due to their high porosity and the availability of injection wells. Much of the CO2 injected into such rocks, however, may remain in the gas phase due to the lack of divalent metals needed to form stable carbonate minerals. As such much of the CO2 injected into such systems could return the surface due to the buoyancy of a CO2 gas phase. In contrast, mafic rocks offer an intriguing possibility for the storage of CO2 due to the large availability of silicate bounded divalent metal cations such as Ca 2+ and Mg2+ which could combine with injected CO2 to form the calcite and Mg carbonate phases. Porosity in mafic rocks, however, tends to be found in fracture networks which pose three challenges: 1) injected CO2 could be highly mobile before it is fixed in mineral phases, 2) precipitation in fractures can clog flow systems, and 3) precipitation of mineral coatings can make fracture walls inert, creating unreactive pathways bringing injected CO2 rapidly back to the surface.
This presentation presents a suite of experimental and geochemical reactive transport results illuminating the likely behavior of the fate of CO2 injected into fractured basaltic rocks. Results are compared to natural analogues of Iceland, where fractured basaltic rocks have reacted with natural CO2 fluxes over geological timeframes. Emphasis will be placed on the current state-of-the art and identifying essential future research directions