Multi-Physics Laboratory Characterization of Preserved Clay- To Carbonate-Rich Shales

Esteban, Lionel (CSIRO Earth Science and Resource Engineering) | Sarout, Joel (CSIRO Earth Science and Resource Engineering) | Josh, Matthew (CSIRO Earth Science and Resource Engineering) | Clennell, Ben (CSIRO Earth Science and Resource Engineering) | Dewhurst, David (CSIRO Earth Science and Resource Engineering) | Marschall, Paul (NAGRA Switzerland) | Raven, Mark (CSIRO Land and Water)


Summary Preserved shale samples of widely varying clay and carbonate content were recovered from a deep geothermal well near the village of Schlattingen in the Molasse Basin of northern Switzerland. The cored borehole section comprised various stratigraphic sequences from Upper Triassic to Lower Jurassic at depths between 725 and 989 m below surface. A laboratory multi-physics assessment was conducted to characterize their mineralogy, texture, porosity distribution between clay-bound water and weakbound water, broad frequency electrical response, and their geomechanical properties. Despite some mineralogical variations within the sample set, the porosity and rock-fluid water interactions depend on the pore size distribution while the geomechanical and electrical responses are mostly controlled by the clay/carbonate content. The borehole is intended for producing geothermal energy for horticulture with low CO2 emissions.