| Popis: |
Summary Two mudrock seals from a site being evaluated for geological storage of CO2 were tested to understand their geomechanical properties, mineralogical composition and geochemical make up before and after immersion in super-critical CO2 (sCO2) at high pressure and temperature (150°C and 4200 psi) representing close to in situ conditions. Physico-chemical properties such as cation exchange capacity and specific surface area were also evaluated. Samples for mineralogy, geochemistry and physico-chemical properties were tested stepwise from their initial state through to 1, 4 and 6 months immersion in sCO2. Samples for geomechanical testing were compared in their initial preserved state and after ageing for 6 months in sCO2. No change in composition was noted for either mineralogy or major element geochemistry and the physico-chemical properties measured were also unchanged. However, geomechanical properties did change, with compressive strength, tensile strength, friction coefficient and elastic stiffness all increasing after exposure to sCO2. As there was no change in mineralogy or geochemistry, it is most likely that the loss of water during exposure to sCO2 resulted in the strength increase observed in these mudrocks. |
